Control apparatus, control method and control program

ABSTRACT

In a control apparatus which transmits/receives data from a central processing unit via a serial transfer channel to a communication control unit, and groups/distributes data of input/output units from the communication control unit via a parallel transfer channel, the control apparatus initiates a diagnosing unit of the parallel transfer channel in response to an instruction issued from the central processing unit, and diagnosis the input/output units subsequent to the diagnosis of the transmission channel. Data input/output timing of the input/output unit is also instructed from the central processing unit, so that the central processing unit can suppress lowering of response speeds caused by the diagnoses, and can maintain the periodicity of the data input/output.

BACKGROUND OF THE INVENTION

The present invention generally relates to a control apparatus, acontrol method, and a control program. More specifically, the presentinvention is directed to a control apparatus, a control method, and acontrol program, which are suitably operable for functional safety.

Very recently, there are many demands capable of realizing suchprogrammable electronic apparatuses capable of securing safety aspectsas to human life and environments. In contract to “intrinsic safety”,such a safety established under an initial condition of normal operationof an apparatus is referred to as “functional safety.” There is noquestion that enlargements capable of applying the so-called “functionalsafety” may depend upon considerable improvements in performance andreliability of electronic appliances.

Effects achieved by applying programmable electronic apparatuses arecaused not only by such a fact that protection logic equipmentsconstructed of conventional mechanical relays can be realized by compactapparatuses with lighter weight and higher reliability than that of theprotection logic equipments, but also by other means. In conventionalmaintenance checkup systems, operations of plant apparatuses whichconstitute protection subjects are stopped in a periodic manner so as tocheck up operations of protection logic equipments. In contrast thereto,based upon self-diagnostic functions utilizing features of electronicapparatuses, the protection logic apparatuses can be diagnosed withoutstopping the plant apparatuses, which may contribute improvements inoperation rates of the plant apparatuses, and also may save man power ofmaintenance works. Such diagnostic techniques have been described in,for instance, JP-A-6-290066.

In view of target characteristics as to safety protections for humanlife and environments, standards capable of determining levels ofobjective functional safety may become major important matters.Establishments of standards started in Europe, and then, nowadays, theinternational standards such as IEC 61508 are being established. In IEC61508, while factors for impeding “functional safety” are mainly dividedinto two impedance factors, the standards of IEC 61508 have definedmeasures and effects of these impedance factors in detail. The firstimpeding factor corresponds to a random failure which is caused byhardware, whereas the second impeding factor corresponds to a systematicfailure which is usually referred to as a “software bug.” Thus, thestandards of IEC 61508 defines diagnostic methods of random failures(first impeding factor) and diagnostic rates corresponding thereto, andfurther defines developing processes capable of preventing thesystematic failures (second impeding factor).

Since users use such products, the users can secure required safetylevels, while these products have been certified by a third institutionwhich has been independently established based upon the internationalstandard. As previously described, the certification of the productsbased upon the functional safety, and the international standardthereof, and the international standard may have higher contributiondegrees.

On the other hand, communication control apparatuses are equipped withinput apparatuses for acquiring equipment data about equipment undercontrol, and a plurality of information processing apparatuses formonitoring, or controlling the appliances based upon the acquiredequipment data. These communication control unit have been utilized inmonitoring/controlling systems for plants. In these communicationcontrol apparatuses, events occurred in the equipment under control arestored; occurrence times of these events are measured by time measuringcounters; and event occurrence times (time stamps) are added to contentsof these events, and then, the resulting event contents are stored asstatus data. If the communication control units analyze these storedstatus data, then occurrences of input events of plural signals can begrasped in a time sequential manner. As a result, even when failureshappen to occur in equipments, the communication control units cancorrectly grasp causes of these failures.

JP-A-2004-356955 discloses such a technical idea capable of defininginput event times in correspondence with input status data

SUMMARY OF THE INVENTION

Generally speaking, in order to cut off such an infinite loop thatrandom failures of diagnosing apparatuses installed in accordance withfunctional safety standards also need to be diagnosed, the followingtechnical ideas have been employed. That is, diagnosing apparatusesconstructed of software are diagnosed by software programs which havebeen developed by a predetermined developing process. As a result, ingeneral, such technical ideas have been employed by whichmicroprocessors are installed not only on logic calculation apparatuses,but also on input/output units, so that the microprocessors executediagnostic programs. To this end, such diagnostic programs must beexecuted which execute not only diagnostic functions but also diagnosethese diagnostic functions in addition to logic calculations andinput/output operations (namely, original functions). Furthermore, theinput/output units must execute the diagnostic programs. As aconsequence, the below-mentioned trends may appear: That is,periodicities about input/outputs and response times of the electronicapparatuses which perform input operations logic calculations, andoutput operations for a series of signals are readily impeded.

More specifically, such users cannot ignore such a fact that theresponse times and the periodities are impeded which constitute thebasic functions as the control apparatuses for securing the functionalsafety, while these users have secured the predetermined controlfunctions and the safety levels by commonly employing one programmableelectronic apparatus which is capable of realizing both the controlfunctions and a part of the protection functions, which may reflectprogress in recent techniques of electronic apparatuses.

An object of the present invention is to provide a control apparatus andcontrol method capable of functional safety, while are capable ofmaintaining basic performance such as response time and periodicity.

Also, in the above-described conventional techniques, counters areemployed for each set of the plural input modules. As a result,general-purpose input modules cannot be used without significantmodification. Further, since the time stamps are defined incorrespondence with each set of these input modules, a large amount ofdata are required. Thus, there is such a problem that the data transferperformance is deteriorated when the data are transferred, inparticular, when the data are transferred via the serial communicationchannels.

An object of the present invention is to provide a control apparatus, acontrol method, and a control program, which are capable of managingtime instant relative information when an event occurs, while arecapable of maintaining transfer performance even when data istransferred via a communication channel.

To achieve the above-described object, a control apparatus, according tothe present invention, is arranged as follows: That is, in a controlapparatus having a communication control unit communicatably connectedto the control apparatus via a first communication channel, at least aportion of which performs a serial transfer operation, in which thecommunication control unit transmits/receives information with respectto an equipment under control via a second communication channel, aportion of which constitutes a parallel transfer operation; the controlapparatus comprised of: a communication channel diagnostic unit fordiagnosing an abnormal event such as an open and stuck-at of a paralleltransfer portion of the second communication channel under such acondition that a data transfer operation in the second communicationchannel is interrupted; in which a signal for instructing an initiationof a diagnosis via the first communication channel is transmitted to thecommunication channel diagnostic unit.

Moreover, a basic arrangement of the control apparatus is arranged byemploying: an input unit and an output unit; the input unittransmitting/receiving data from a central processing unit via a firstcommunication channel, at lest a portion of which constitutes a serialtransfer operation, with respect to a communication control unit, andgrouping, or distributing the data from the communication control unitof the transmission/reception destination so as to measure an equipmentunder control via a second communication channel, at least a portion ofwhich constitutes a parallel transfer operation; and the output unitoutputting to the equipment under control via the second communicationchannel.

In this control apparatus, a parallel transfer operation which issuitable for a high-speed transfer operation compared to a serialtransfer operation is employed in an input/output bus between thecommunication control unit and the input/output units. To secure thefunctional safety, a diagnosis of this parallel transfer unit isrequired. In order to perform a diagnosis, the most reliable method isto diagnose a physical open and stuck-at of the parallel transferringunit, although a data transfer operation must be stopped during adiagnosing period. In order to set start timing of the diagnosing periodso as not to give an adverse influence to response times andperiodicities as the control apparatus, the diagnosing operation fordiagnosing the open and stuck-at event of the parallel transferring unitis initiated via the control bus (communication channel 1) from thecentral processing unit.

Also, in this control apparatus, such a serial transfer operation havinga high freedom degree of a transfer distance is employed in the controlbus between the central processing unit and the communication controlunit. To secure the functional safety, transfer errors and masqueradesof this serial transferring unit must be detected. To this end,transmission/reception stations traveled through this serial transferpath must be confirmed and data identifications are required. In orderthat a series of serial transfer operations does not give adverseinfluences to the response times and the periodicities as the controlapparatus, such an input buffer is provided which temporarily stores theinput data from the input unit and outputs the stored data via theinput/output buses (communication channel 2). Then, the input dataupdating operation is stopped from the central processing unit via thecontrol bus and the input bus so as to secure the periodicity of theinput bus. In addition, the data is transferred from the input unit viathe input/output buses to the communication control unit, and the serialtransfer operation corresponding to the functional safety is carried outbetween the communication control unit and the central processing unit.When the serial transfer operation is accomplished, the data updatingoperation of the input buffer is restarted from the central processingunit to the communication control unit, so that both the controlperformance and the functional safety can be established at the sametime.

Also, such an output buffer is provided which temporarily stores theoutput data from the input/output bus (communication channel 2) andoutputs the stored data to the output unit. After the data is writtenfrom the central processing unit via the control bus and theinput/output bus into the output buffer, the data output of the bufferis held; the serial transfer operation corresponding to the functionalsafety is continued between the communication control unit and thecentral processing unit; the transmission/reception stations areconfirmed; and also, the data identification is carried out. When theserial transfer operation is confirmed to have been performed undernormal condition, the data outputting operation of the output buffer ispermitted from the central processing unit to the communication controlunit so as to secure the periodicity of the output data of the outputunit. As a result, the communication control unit is arranged by thatboth the control performance and the functional safety can beestablished at the same time.

Also, a communication control unit, according to another aspect of thepresent invention, is arranged as follows: That is, while informationtransmitted/received with respect to an equipment under control isstored in an information storage unit, information related to timeinstant information is stored in a time instant relative informationstorage unit; the information stored in the information storage unit istransmitted, or the received information is stored in the informationstorage unit; and information stored in the information storage unit isrelated to the information held by the time instant relative informationstorage unit by transmitting/receiving the information via thecommunication channel, at least a portion of which constitutes a serialtransfer operation.

Concretely speaking, the control apparatus having such a basicarrangement is to solve the above-described problem. The basicarrangement consists of a central processing unit, a communicationcontrol unit, a first communication channel, at least a portion of whichperforms serial transfer operation, a second communication channel, atleast a portion of which performs parallel transfer operation, an inputunit and an output unit, where the first communication channel transmitsand receives data between the central processing unit and thecommunication control unit, where the second communication channelcollects and distributes data between the communication control unit,the input unit and the output unit, where input unit performsmeasurement of (data input from) the equipment under control and wherethe output unit performs data output to the equipment under control. Atime measuring counter is provided not in either the input unit or theoutput unit, but is mounted on the communication control unit, which isthe transmission/reception destination from the central processor unit.Furthermore, an input buffer for temporarily storing the input data, anda time measuring buffer for temporarily storing the count value of thetime measuring counter are provided, and then, the data updatingoperations of these buffers are permitted at the same time.

Also, a control apparatus is arranged by employing: means fortransmitting one time measuring value and a plurality of input values toa communication control unit as a transmission/reception destination;and means for expanding one time measuring value to the plurality ofinput values in a communication control unit as a transmission/receptionsource.

While the basic function as to the control apparatus such as either aresponse time or a periodicity is maintained, the functional safety canbe realized. In particular, the control apparatus is suitable to achievethat the high-performance control function and the functional safetycapable of realizing the maintenance diagnosis of the equipment withoutstopping the plant can be established at the same time. Thehigh-performance control function is capable of secure the response timeand the periodicity from the control input to the output by combiningthe serial transfer operation capable of realizing the distributedarrangement of the central processing unit and the input/output unitswith the parallel transfer operation capable of realizing the high-speedplant input/output operations.

Also, even when data is transferred via a communication channel, thetime instant relative information such as the occurrence of the eventcan be managed. Moreover, such a control apparatus can be realized whichcan establish a high-performance control function and an acquisition ofan input/output time instant (time stamp) at the same time. Thehigh-performance control function is capable of secure the response timeand the periodicity from the control input to the output by combiningthe serial transfer operation capable of realizing the distributedarrangement of the central processing unit and the input/output unitswith the parallel transfer operation capable of realizing the high-speedplant input/output operation.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram for showing an arrangement of a controlapparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram for representing a path of control bus(communication channel 1) transmission/reception data of the firstembodiment of the present invention.

FIG. 3 is a time chart for representing operations as to the control bus(communication channel 1) transmission/reception data of the firstembodiment of the present invention.

FIG. 4 is a block diagram for indicating an input/output bus(communication channel 2), and a data path of an input unit of the firstembodiment of the present invention.

FIG. 5 is a block diagram for representing the input/output bus(communication channel 2), and a data path of an output unit of thefirst embodiment of the present invention.

FIG. 6 is a time chart for representing a bus diagnostic instructionoperation performed via the control bus (communication channel 1) of thefirst embodiment of the present invention.

FIG. 7 is a block diagram for showing a normal input operation of theinput unit according to the first embodiment of the present invention.

FIG. 8 is a block diagram for representing a test operation of the inputunit according to the first embodiment of the present invention.

FIG. 9 is a block diagram for indicating a diagnostic operation of theinput unit according to the first embodiment of the present invention.

FIG. 10 is a block diagram for showing a normal input operation of theoutput unit according to the first embodiment of the present invention.

FIG. 11 is a block diagram for representing a test operation of theoutput unit according to the first embodiment of the present invention.

FIG. 12 is a block diagram for indicating a diagnostic operation of theoutput unit according to the first embodiment of the present invention.

FIG. 13 is a block diagram for showing an arrangement of an input unitaccording to a second embodiment of the present invention.

FIG. 14 is a time chart for representing an input operation according tothe second embodiment of the present invention.

FIG. 15 is a block diagram for indicating an arrangement of an outputunit according to a third embodiment of the present invention.

FIG. 16 is a time chart for representing an output operation accordingto the third embodiment of the present invention.

FIG. 17 is a block diagram for showing an arrangement of a controlapparatus according to a fourth embodiment of the present invention.

FIG. 18 is a block diagram for representing a path of control bus(communication channel 1) transmission/reception data of the fourthembodiment of the present invention.

FIG. 19 is a time chart for representing operations as to the controlbus (communication channel 1) transmission/reception data of the fourthembodiment of the present invention.

FIG. 20 is a block diagram for indicating an input/output bus(communication channel 2), and a data path of an input unit of thefourth embodiment of the present invention.

FIG. 21 is a block diagram for representing the input/output bus(communication channel 2), and a data path of an output unit of thefourth embodiment of the present invention.

FIG. 22 is a block diagram for showing an arrangement of a communicationcontrol unit “P0” according to the fourth embodiment of the presentinvention.

FIG. 23 is a block diagram for showing an arrangement of the input unitaccording to the fourth embodiment of the present invention.

FIG. 24 is a time chart for representing an input operation according tothe fourth embodiment of the present invention.

FIG. 25 is a block diagram for indicating an arrangement of an outputunit according to a fifth embodiment of the present invention.

FIG. 26 is a time chart for representing an output operation accordingto the fifth embodiment of the present invention.

FIG. 27 is a time chart for representing a synchronizing method of timeinstants according to a sixth embodiment of the present invention.

FIG. 28 is a block diagram for showing an arrangement of an input unitaccording to the sixth embodiment of the present invention.

FIG. 29 is a time chart for representing an input operation according tothe sixth embodiment of the present invention.

FIG. 30 is a block diagram for indicating an arrangement of an outputunit according to a seventh embodiment of the present invention.

FIG. 31 is a time chart for representing an output operation accordingto the seventh embodiment of the present invention.

FIG. 32 is a block diagram for showing an arrangement of a communicationcontrol unit “P0” according an eighth embodiment of the presentinvention.

FIG. 33 is a block diagram for indicating an input/output bus(communication channel 2), and a data path of an input unit of a tenthembodiment of the present invention.

FIG. 34 is a block diagram for representing the input/output bus(communication channel 2), and a data path of an output unit of aneleventh embodiment of the present invention.

DESCRIPTION OF THE INVENTION

Referring now to drawings, various embodiments of the present inventionwill be described in detail.

First Embodiment

A control apparatus according to a first embodiment of the presentinvention is indicated in FIG. 1. A central processing unit (CPU) 1 isconnected via a parallel transfer bus 0 (communication channel “0”) to acommunication control unit 3 (“P0”). The communication control unit 3(“P0”) transmits and/or receives data via a control bus 2 (communicationchannel “1”) using a serial transfer operation with respect to acommunication control unit 4 (“S1”), and another communication controlunit 7 (“S2”).

The communication control unit 4 (“S1”) and an input unit transmitand/or receive input data and a control signal supplied from anequipment under control 6 via an input/output bus 5 (communicationchannel “2”) using a parallel transfer operation. The communicationcontrol unit 7 (“S2”) and an output unit transmit and/or receive inputdata and a control signal to be supplied to the equipment under control6 via an input/output bus 8 (communication channel “2”) using a paralleltransfer operation.

The input unit is constituted by “n” pieces of input devices 9, 10, and11 (1 to n). The respective input devices transmit and/or receive inputdata from the equipment under control 6 via the input/output bus 5(communication channel 2) with respect to the communication control unit4 (S1). Similarly, the output unit is constituted by “m” pieces ofoutput devices 12, 13, and 14 (1 to m). The respective output devicestransmit and/or receive output data to the equipment under control 6 viathe input/output bus 8 (communication channel 2) with respect to thecommunication control unit 7 (S2).

A communication channel diagnostic unit 41 for diagnosing an open orstuck-at failure of the input/output bus 5 (communication channel 2) isactivated in response to a control signal 42 supplied from thecommunication control unit 4 (S1). Also, a selecting switch 44 switchesfrom contact “C” to contact “D” in response to a control signal 43. Thecommunication channel diagnostic unit 41 corresponds to such an unitwhich is installed on one terminal end of the input/output bus 5(communication line 2) so as to circulatedly diagnose a paralleltransferring circuit of the input/output bus 5 (communication channel2). For instance, the communication channel diagnosing unit 41 adds atest pattern for diagnosis which switches a signal level of a “k”thtransfer path and fixes all levels of other signals to levels “H.” Next,the communication channel diagnostic unit 41 fixes the all levels ofother signals to levels “L”, and again applies the signal pattern fordiagnosis to the “k”th transfer path. A receive unit 45 provided at theother end portion serial-converts reception signal patterns for not onlythe “k”th transfer path, but also all of the communication paths, andthen, transfers the serial-converted reception signal patterns via thetransfer path 46 to the communication channel diagnostic unit 41. Thecommunication channel diagnostic unit 41 monitors whether or not a “k”threception signal pattern is identical to the signal pattern fordiagnose, and also monitors whether or not signals of othercommunication paths are not influenced by the signal pattern fordiagnosis. A result of the above-described diagnoses is notified via thetransfer path 46 to the communication control unit 4 (S1). If thediagnosis result is normal, then the selecting switch 44 is connected tocontact “C” in order that the communication of the communication channeldiagnostic unit 41 restarts a communication with the input/output bus 5(communication line 2). Next, when the transfer channel diagnostic unit41 is activated, the signal pattern for diagnosis is added to a (k+1)thtransfer path. As previously explained, a stopping time period of theinput/output bus 5 (communication channel 2) can be shortened bycirculatedly diagnosing the transfer path.

Another communication channel diagnostic unit 71 which diagnoses an openor stuck-at failure of the input/output bus 8 (communication channel 2)is activated by receiving a control signal 72 supplied from thecommunication control unit 7 (S2). An operation of the communicationchannel diagnostic unit 71 and an operation of a receive unit 75 areidentical to those of the communication channel diagnostic unit 41 andthe receive unit 45, so that descriptions thereof are omitted.

FIG. 2 indicates a path of data transmitted/received between thecommunication control unit 3 (P0) and the communication control units 4(S1) and 7 (S2) via the control bus 2 (communication channel 1) usingthe serial transfer operation. With respect to a communication memory 38provided in the communication control unit 3 (P0), regions used for asequence number-purpose memory 381, an input data-purpose memory 382, anoutput data-purpose memory 383, and a read back data-purpose memory 384are allocated. Data stored in the communication memory 38 isparallel/serial-converted by a communication control circuit 39, andthen, parallel/serial-converted data is transferred via the control bus2 (communication channel 1) between communication memories 48 and 78 ofthe communication control units 4 (S1) and 7 (S2).

With respect to the communication memory 48 employed in thecommunication control unit 4 (S1), regions used for a sequencenumber-purpose memory 481 and an input data-purpose memory 482 areallocated. Data of the input data-purpose memory 482 within thecommunication memory 48 is parallel/serial-converted by a communicationcontrol circuit 49, and then, the parallel/serial-converted data ismapped to the input data-purpose memory region 382 of the communicationmemory 38 of the communication control unit 3 (P0) via the control bus 2(communication channel 1).

With respect to the communication memory 78 provided in thecommunication control unit 7 (S2), regions used for a sequencenumber-purpose memory 781, an output data-purpose memory 783, a readback data-purpose memory 784, and a temporary holding memory 785 areallocated. Data stored in the output data-purpose memory region 383 ofthe communication memory 38 of the communication control device 3 (P0)is parallel/serial-converted by the communication control circuit 79,and then, the parallel/serial-converted data is transferred via thecontrol bus 2 (communication line 1) to the temporary holding memory 785of the communication memory 78. Data stored in the temporary holdingmemory 785 is transferred to the output data-purpose memory 783 aftersuch a confirmation is made that a communication between thecommunication control units 3 (P0) and 7 (S2) is normal. Data stored inthe read back data-purpose memory 784 is transferred to the readback-purpose memory 384 of the communication control unit 3 (P0).

FIG. 3 indicates a data communication operation sequence executed amongthe communication control units 3 (P0), 4 (S1), and 7 (S2) via thecontrol bus 2 (communication channel 1).

At a time “t1”, an input request “IR (1, N)” from the communicationcontrol unit 3 (P0) to the communication control unit 4 (S1) isoutputted to the control bus 2 (communication channel 1).

The input request IR (1, N) is made of a data string as to a send key(SendKey=0) corresponding to a sender number 0; a receive key(Rcv.Key=1) corresponding to a receiver number 1; a sequence number(Seq.No.=N) used to confirm a transfer data sequence; input deviceinformation (Dev.Adr.) of a transfer destination from the communicationcontrol unit 4 (S1); and an input data size (DataSize). In addition,both a start flag and an end flag which are commonly used in alltransfer data are added to a head portion and a tail portion of a datastring. However, for the sake of simplicity, indications of these flagsare omitted. In this case, the input device information (Dev.Adr.)constitutes n-bit ON/OFF data in the first embodiment shown in FIG. 1.For instance, when the input device information is inputted from theinput device 1, the n-bit ON/OFF data is transferred while first bitdata is set to “1”, whereas when the input device information is notinputted from the input device 2, the n-bit ON/OFF data is transferredwhile second bit data is set to “0.”

The communication control unit 4 (S1) recognizes that a request isissued for the own equipment based upon the receive key (Rev.Key=1) ofthe input request IR (1, N), and then, outputs an input request echo IE(I, N) to the control bus 2 (communication line 1).

The input request echo IE (1, N) is constituted by a data string as toan input request echo command (IE), a send key (SendKey=1) correspondsto a sender number 1, a receive key (Rcv.Key=0) corresponding to areceiver number 0, and a sequence number (Seq.No.=N) used to confirm atransfer data sequence.

The communication control unit 3 (P0) confirms that the input request IR(1, N) has been transferred to the communication control unit 4 (S1)under normal condition by checking that the send key and the receive keyof the input request echo IE (1, N) are reversed to those of the inputrequest IR (1, N), and the sequence number (Seq.No.=N) thereof is notchanged.

As previously explained, the reversed send key and the reversed receivekey are used in order to monitor a camouflage (masquerade) of acommunication. Also, a time out of a transfer operation is monitored bya communication timer 1 which is operated by sending the input requestIR (1, N) and receiving the input request echo IE (1, N).

At a time instant “t2”, an input access request ID (1, N) from thecommunication control unit 3 (P0) to the communication control unit 4(S1) is outputted to the control bus 2 (communication channel 1).

The input access request ID (1, N) is constituted by a data string as toan input request echo command (IA), a send key (SendKey=0) correspondsto a sender number 0, a receive key (Rcv.Key=1) corresponding to areceiver number 1, and a sequence number (Seq.No=N) used to confirm atransfer data sequence.

The communication control unit 4 (S1) recognizes that a request isissued for the own equipment based upon the receive key (Rcv.Key=1) ofthe input access request ID (1, N), and outputs an input access data IA(1, N) read out from the input data-purpose memory 482 to the controlbus 2 (communication channel 1).

The input access data IA (1, N) is constituted by such a data string.That is, the data string is made by an input access request command(IA), a send key (SendKey=1) corresponding to a sender number 1, areceive key (Rcv.Key=0) corresponding to a receiver number 0, a sequencenumber (Seq.No.=N) for confirming a transfer data sequence, input deviceinformation (Dev.Adr.) and an input data size (DataSize) equal to theinput request IR (1, N), and finally, input data (InputData).

The communication control unit 3 (P0) confirms the send key and thereceive key, the sequence number (Seq.No.=N), the input deviceinformation (Dev.Adr.), the input data size (DataSize) of the inputaccess data IA (1, N).

When a confirmation result is normal, the input data (InputData) iswritten in the input data-purpose memory 382 employed in thecommunication control unit 3 (P0). The sequence number is counted up tobecome (Seq.No.=N+1). The central processing unit 1 (CPU) can read theinput data from the input data-purpose memory 382 at timing controlledby a program.

During the above-described process operation, the communication timer 1is operated based upon the input access request ID (1, N) and the inputaccess request command IA (1, N). Also, the communication timer 2monitors a time out of the input communication by sending the inputrequest IR (1, N) and by receiving the input access data IA (1, N).

At a time instant “t3”, an output request QR (2, N+1) from thecommunication control unit 3 (P0) to the communication control unit 7(S2) is outputted to the control bus 2 (communication channel 1).

The output request QR (2, N+1) is constituted by such a data string asto an output request command (QR), a send key (SendKey=0) correspondingto a sender number 0, a receive key (Rcv.Key=2) corresponding to areceiver number 2, a sequence number (Seq.No.=N+1), output deviceinformation (Dev.Adr.) of a transfer destination from the communicationcontrol unit 7 (S2), an output data size (DataSize), and output data(OutputData). The output data (OutputData) is written from the outputdata-purpose memory 383.

In this case, the output device information (Dev.Adr.) constitutes them-bit ON/OFF data in the first embodiment of FIG. 1.

The communication control unit 7 (S2) recognizes that a request for theown equipment is issued based upon the receive key (Rcv.Key=2) of theoutput request QR (2, N+1), and writes the output data (OutputData) tothe temporary holding memory 785 provided in the communication controlunit 7 (S2). Also, the communication control unit 7 (S2) outputs anoutput request echo QE (2, N+1) to the control bus 2 (communicationchannel 1).

The output request echo QE (2, N+1) is constituted by such a data stringas to an output request echo command (QE), a send key (SendKey=2), areceive key (Rcv.Key=0), and a sequence number (Seq.No.=N+1).

The communication control unit 3 (P0) confirms that the output requestQR (2, N+1) has been normally transferred to the communication controlunit 7 (S2) based upon the output request QR (2, N+1), the send key andthe receive key of the output request echo QE (2, N+1), and the sequencenumber (Seq.No.=N+1). The communication timer 1 is operated based uponthe output request QR (2, N+1) and the output request echo QE (2, N+1).

Page 15

At a time instant “t4”, an output access request QD (2, N+1) from thecommunication control unit 3 (P0) to the communication control unit 7(S2) is outputted to the control bus 2 (communication channel 1).

The output access request QD (2, N+1) is constituted by such a datastring as to an output access request command (QA), a send key(SendKey=0) corresponding to a sender number 0, a receive key(Rcv.Key=2) corresponding to a receiver number 2, a sequence number(Seq.No.=N+1) used to confirm a transfer data sequence.

The communication control unit 7 (S2) recognizes that an output requestfor the own equipment is issued based upon the receive key (Rcv.Key=2)of the output access request QD (2, N+1) and the sequence number(Seq.No.=N+1), and then, outputs the data stored in the temporaryholding memory 785 provided in the communication control unit 7 (S2) tothe output data-purpose memory 783. Also, the communication control unit7 (S2) outputs the output access request data QA (2, N+1) to the controlbus 2 (communication channel 1).

The output request echo QA (2, N+1) is constituted by such a data stringas to an output access request command (QA), a send key (SendKey=2), areceive key (Rcv.Key=0), and a sequence number (Seq.No.=N+1), an outputaccess request QA (2, N+1), output device information (Dev.Adr.), anoutput data size (DataSize), and finally, an output echo back(OutputEchoback) written from the temporary holding memory 785.

The communication control unit 3 (P0) confirms the send key and thereceive key of the output access data QA (2, N+1), the sequence number(Seq.No.=N+1), the output device information (Dev.Adr.), and the outputdata size (DataSize). When a confirmation result becomes normal, thesequence number is counted up (Seq.No.=N+2).

During the above-described process operation, the communication timer 1is operated based upon the output access request QD (2, N+1) and theoutput access data QA (2, N+1). Also, the communication timer 2 monitorsa time out of the output communication by sending the output request QR(2, N+1) and by receiving the output access data QA (1, N+1).

In the first embodiment of FIG. 1, since the output echo back(OutputEchoback) is added to the output access data QA (2, N+1), thecommunication control unit 3 (P0) can compare the added data with theoutput data (OutputData), so that the communication control unit 3 (P0)can confirm that the output data has been transferred under the normalcondition.

A time period defined from a time instant “t5” to a time instant “t7”indicates an input communication in the case that an output read backfunction is provided with a portion, or all of the output devices 12,13, 14 (1 to m) of the output unit.

A difference between the above-described input communication of the timeperiod from the time instant “t1” to the time instant “t3” and thisinput communication of the time period from the time instant “t5” to thetime instant “t7” is given as follows in addition to the sequencenumbers: That is, the counter party of the communication control unit 3(P0) is the communication control unit 7 (S2) with respect to thecommunication control unit 4 (S1); and the input device information(Dev.Adr.) is the m-bit ON/OFF data with respect to the n-bit ON/OFFdata; and the output read back data (OutputEchoback) corresponds to theinput data (InputData). Also, the m-bit data of the input deviceinformation (Dev.Adr.) indicates whether or not the output read backdata of the output devices 12, 13, 14 (1 to m) are present. Otheraspects of the input communication are identical to those of the inputcommunication defined from the time instant t1 to the time instant t3.Concrete data strings are given as follows:

With execution of the above-described communication operations, the datacommunication among the communication control units 3 (P0), 4 (S1), and7 (S2) via the control bus 2 (communication channel 1) is circulatedlycarried out, and then, at the time instant t7, the same operation asthat of the time instant t1 is commenced. It should also be noted thatthis communication operation is the same as that of the time instant t1except that a sequence number becomes (Seq.No.=N+3). As previouslyexplained, the data transferring operation via the control bus 2(communication channel 1) corresponds to the memory transferringoperation executed in a predetermined periodic operation sequence, andthe operation sequence from the time instant t1 to the time instant t6is not reversed, but also is not omitted. As a result, the sequentialcontrol of the data strings is not required, so that idle times betweenthe data strings can be minimized, and the transfer efficiency can beincreased.

It should be understood that in the reset timing (t1, t2, - - - , t6) ofthe communication timer 1, other communication commands may bealternatively interrupted. Also, in this alternative case, an operationsequence of a memory transferring operation is not reversed, but also isnot omitted except that a completion of the interrupted communicationcommand is merely waited.

FIG. 4 indicates a path of data transmitted/received between thecommunication control unit 4 (S1) and an input unit via the input/outputbus 5 (communication channel 2). Each of “n” pieces of the input devices9, 10, 11 (1 to n) which constitute the input unit is equipped with aninput register 91, another input register 101, and a further inputregister 111 respectively, while measurement data from the equipmentunder control 6 is written into the input registers 91, 101, 111 ineither timing or a time period in correspondence with structures ofthese input devices 91, 101, 111. The measurement data stored in theinput registers 91, 101, 111 are transferred in a periodic manner viathe input/output bus 5 (communication channel 2) to the inputdata-purpose memory region 482 of the communication memory 48 of thecommunication control unit 4 (S1). It should be understood that whilethe input/output bus is under stopping condition, for example, while thecommunication channel diagnostic equipment 41 is under operation, thedata transferring operation is also stopped. Generally speaking, a datatransfer time period via the input/output bus 5 (communication channel2) is considerably shorter than a data transfer time period via thecontrol bus 2 (communication channel 1). As a result, after the datatransfer operation is again initiated, the data transfer operation maybe continuously commenced from a specific input register, for example,the input register 91. As a consequence, a buffer function of theinput/output bus 5 (communication channel 2) as to the data transferoperation may be simplified.

FIG. 5 indicates a path of data transmitted/received between thecommunication control unit 7 (S2) and an output unit via theinput/output bus 8 (communication channel 2). Each of “m” pieces of theoutput devices 12, 13, 14 (1 to m) which constitute the output unit isequipped with an output register 121, another output register 131, and afurther output register 141 respectively, while data is outputted to theequipment under control 6 in either timing or a time period incorrespondence with structures of the output devices 12, 13, 14 (1 tom). Data stored in the output data-purpose memory region 783 of thecommunication memory 78 of the communication control unit 7 (S2) istransferred via the input/output bus 8 (communication channel 2) to theoutput registers 121, 131, 141 in a periodic manner. On the other hand,in the first embodiment of FIG. 5, the respective output devices 12, 13,14 (1 to m) have been equipped with the functions capable of readingback outputs to the equipment under control 6. The read back results arewritten in the read back registers 122, 132, 142, and are transferredvia the input/output bus 8 (communication channel 2) to the read backdata-purpose memory region 784 of the communication memory 78 of thecommunication control unit 7 (S2) in a periodic manner. It should alsobe understood that while the input/output bus is under stoppingcondition, for example, while the communication channel diagnostic unit71 is under operation, the data transferring operation is also stopped.Similar to the input/output bus 5 (communication channel 2), generallyspeaking, a data transfer time period via the input/output bus 5(communication channel 2) is considerably shorter than a data transfertime period via the control bus 8 (communication channel 1). As aresult, after the data transfer operation is again initiated, the datatransfer operation may be continuously commenced from a specific outputregister, for example, the output register 121.

As indicated in FIG. 2, FIG. 3, FIG. 4, and FIG. 5, any of the controlbus 2 (communication channel 1), the input/output bus 5 (communicationchannel 2), and the input/output bus 8 (communication channel 2) havebeen made of such a basic structure that the specific memorytransferring operations can be independently carried out.

FIG. 6 indicates an operation sequence for activating both thecommunication channel diagnostic unit 41 of the input unit and thecommunication channel diagnostic unit 71 of the output unit via thecontrol bus 2 (communication channel 1).

It should be understood that since the same symbols as to the datastrings and the timing shown in FIG. 3 as those indicated in FIG. 6represent the same contents, descriptions thereof are omitted in orderto avoid overlapped explanations.

In the first embodiment of FIG. 6, in accordance with the communicationcontrol program of the communication control unit 3 (P0), thecommunication channel diagnostic unit 41 is activated after an inputdata communication from the communication control unit 7 (S2) has beenaccomplished, and the communication channel diagnostic unit 71 isactivated after an output read back data communication from thecommunication control unit 7 (S2) has been initiated. Also, the firstembodiment of FIG. 6 has been constructed as follows: That is, aconfirmation is made that the input/output bus 5 (communication channel2) can be operated (completion of preparation) before the input datacommunication from the communication control unit 4 (S1) is commenced,and also, a confirmation is made that the input/output bus 8(communication channel 2) can be operated (completion of preparation)before the output data communication to the communication control unit 7(S2) is commenced.

At a time instant “tc1”, a bus diagnosis command “R (1, BD)” istransferred to the communication control unit 4 (S1) in accordance withthe communication control program of the above-described communicationcontrol unit 3 (P0).

Page 18

The bus diagnosis command R (1, BD) is constituted by a diagnosisrequest command (BD), a send key (SendKey=0), and a receive key(Rcv.Key=1). This is no sequence number for a transfer operation whichis inserted as an interrupt.

The communication control unit 4 (S1) recognizes a request for the ownequipment based upon the receive key (Rcv.Key=1) of the bus diagnosiscommand R (1, BD), and outputs a diagnosis request echo “E (1, BD)” tothe control bus 2 (communication channel 1).

The diagnosis request echo E (1, BD) is constituted by a diagnosisrequest command (BD), a send key (SendKey=1), and a receive key(Rcv.Key=0).

The communication channel diagnostic unit 41 is activated by a controlsignal 42 at the same time when the diagnosis request echo E (1, BD) isissued, and the selecting switch 44 is connected to the side D by thecontrol signal 43. With execution of the above-described processoperation, the communication channel diagnosis of the input unit iscommenced.

At a time instant “tc2”, a bus preparation completion accessconfirmation “D (2, BA)” is transferred to the communication controlunit 7 (S2).

The bus preparation completion access confirmation D (2, BA) isconstituted by a bus access command (BA), a send key (SendKey=0), and areceive key (Rcv.Key=2).

The communication control unit 7 (S2) confirms a request for the ownequipment based upon the receive key (Rcv.Key=2) of the bus preparationcompletion access confirmation D (2, BA), and outputs a diagnosisrequest echo A (2, BA) to the control bus 2 (communication channel 1).

The diagnosis request echo A (2, BA) is constituted by a bus accesscommand (BA), a send key (SendKey=2), a receive key (Rcv.Key=0), andsubsequently a status signal (Status). The status signal is made of an(m+1)-bit ON/OFF signal, while the respective bits indicate diagnosticoperation statuses of the communication channel diagnostic unit 71, anddiagnostic operation statuses of the output devices 12, 13, 14 (1 to m).A diagnostic status becomes 1, and a normal operation status becomes 0.As a consequence, when all of these bits become 0, a preparation of anoutput unit which is connected to the communication control unit 7 (S2)is completed.

From a time instant t3′ to a time instant t6′, a data transfer operationis continuously carried out, which is identical to that from the timeinstant t3 to the time instant t6 of FIG. 2.

At a time instant “tc3”, a bus diagnosis command “R (2, BD)” istransferred to the communication control unit 7 (S2) in accordance withthe communication control program of the above-described communicationcontrol unit 3 (P0) so as to activate the communication channeldiagnostic unit 71. The operation is identical to the above-describedoperation when the communication channel diagnostic unit 41 is activatedat the time instant “tc1”, and thus, only a data string is indicated inorder to avoid the duplicated explanation.

FIG. 7 indicates an internal arrangement of the input device 9 of thefirst embodiment. A measurement signal derived from the equipment undercontrol 6 is converted by a converting circuit 201, and then, theconverted measurement signal is written in an input register 91 employedin a signal input circuit 202. A memory transfer operation from theinput register 91 via the input/output bus 5 (communication channel 2)to the communication control unit 4 (S1) is similar to that aspreviously described with reference to FIG. 4. In the above-describedbasic arrangement, when the normal data input operation is performed,both the switch 203 and the switch 204 are connected to the sides C.

FIG. 8 shows a test of an input diagnosis circuit 205 provided in theinput device 9, according to the first embodiment. The test of the inputdiagnosis circuit 205 is carried out after the diagnosis by thecommunication channel diagnostic unit (otherwise, will also be referredto as “bus diagnostic equipment”) 41 activated in the operation sequenceof FIG. 6 has been accomplished. Both the selecting switch 203 and theselecting switch 204 are connected to the sides D. A comparator 206employed in the input diagnosis circuit 205 compares an inputdiagnosis-purpose signal 207 with such a signal which is produced by aprogram of the communication control unit 4 (S1) and then is inputted tothis comparator 206 via the input/output bus 5 (communication line 2).From the program, both a coincident signal and a non-coincident signalby the comparator 206 are produced, so that such a diagnosis can becarried out by the comparator 206, which includes a check for judgingwhether or not an output stuck-at failure is present.

FIG. 9 indicates an input diagnosis executed by the input diagnosiscircuit 205 provided in the input device 9, according to the firstembodiment. The input diagnosis is carried out after the test of FIG. 8has been accomplished. The selecting switch 203 is connected to the sideD, and the switch 204 is connected to the side C. The inputdiagnosis-purpose reference signal 207 and a signal derived from theinput register 91 are inputted to the comparator 206 for a comparisonpurpose. If the input device 9 is operated under normal condition, thenthese signals are coincident with each other. As the inputdiagnosis-purpose reference signal 207, it is so arranged that aplurality of reference signals are sequentially outputted. That is tosay, in the case of digital inputs, both an ON signal and an OFF signalare generated, whereas in the case of analog inputs, reference signalshaving a plurality of levels are generated. As a result, such adiagnosis including the output stuck-at failure of the signal inputcircuit 202 can be carried out.

When the test of FIG. 8 and the diagnosis of FIG. 9 are accomplished,the bit of the diagnosis operation status signal which is transmitted tothe communication control unit 4 (S1) becomes “0” indicative of thenormal operation status. In response to an activation instruction issuedfrom the communication control unit 4 (S1) via the input/output bus 5(communication channel 2), the diagnosis operation can be returned tothe normal input operation.

FIG. 10 represents an internal arrangement of the output device 12,according to the first embodiment. A memory transfer from thecommunication control unit 7 (S2) via the input/output bus 8(communication channel 2) to an output register 121 employed in thesignal output circuit 301 is similar to that as explained in FIG. 5.Data of the output register 121 is supplied via a data holding circuit302 so as to be converted by a converting circuit 303, and then, theconverted data is written in a read back register 122. In theabove-described basic arrangement, when a normal data output operationis performed, the data holding circuit 302 is not operated, and an inputsignal is identical to an output signal. Also, any of selecting switches305, 306, and 307 are connected to sides C.

FIG. 11 shows a test of an output diagnosis circuit 308 produced in theoutput device 12, according to the first embodiment. The test of theoutput diagnosis circuit 308 is carried out after the diagnosis by thecommunication channel diagnostic unit 71 activated in the operationsequence of FIG. 6 has been accomplished. Any of the selecting switches305, 306, 307 are connected to sides D. The data holding circuit 302 isswitched to an operation condition so as to hold an output just beforethe test is carried out. A comparator 309 employed in the outputdiagnosis circuit 308 compares an output diagnosis-purpose signal 310with such a signal which is produced by a program of the communicationcontrol unit 7 (S2) and then is inputted to this comparator 309 via theinput/output bus 8 (communication line 2). From the program, both acoincident signal and a non-coincident signal by the comparator 309 areproduced, so that such a diagnosis can be carried out by the comparator309, which includes a check for judging whether or not an outputstuck-at failure is present.

FIG. 12 indicates an output diagnosis executed by the output diagnosiscircuit 309 provided in the input device 12, according to the firstembodiment. The input diagnosis is carried out after the test of FIG. 11has been accomplished. The selecting switch 305, 307 are connected tothe sides D, and the switch 306 is connected to the side C. The dataholding circuit 302 continues the operation status so as to hold anoutput just before the test is carried out. An output diagnosis-purposereference signal 310 and an output signal of a signal output circuit 301which is supplied via an output register 121 are inputted to thecomparator 309 for a comparison purpose. If the output device 12 isoperated under normal condition, then these signals are coincident witheach other. As the output diagnosis-purpose reference signal 310, it isso arranged that a plurality of reference signals are sequentiallyoutputted. That is to say, in the case of digital inputs, both an ONsignal and an OFF signal are generated, whereas in the case of analoginputs, reference signals having a plurality of levels are generated. Asa result, such a diagnosis including the output stuck-at failure of thesignal output circuit 301 can be carried out.

When the test of FIG. 11 and the diagnosis of FIG. 12 are accomplished,the bit of the diagnosis operation status signal which is transmitted tothe communication control unit 7 (S2) becomes “0” indicative of thenormal operation status. In response to an activation instruction issuedfrom the communication control unit 7 (S2) via the input/output bus 8(communication channel 2), the diagnosis operation can be returned tothe normal input operation.

In accordance with the first embodiment shown in FIG. 7 to FIG. 12,subsequent to the diagnosis of the input/output bus, both the inputdevice and the output device are tested and diagnosed, so that the inputunit and output unit can be diagnosed without deteriorating the controlperformance. Also, the plurality of input devices and the plurality ofoutput devices can be tested and diagnosed based upon the programs whichare executed by the communication control unit 4 (S1) and thecommunication control unit 7 (S2). As a consequence, it is not requiredto provide diagnose-purpose microprocessors in the respective inputdevices and the respective output devices.

Second Embodiment

FIG. 13 indicates a control apparatus according to a second embodimentof the present invention. It should be understood that the samereference numerals shown in FIG. 4 will be employed as those fordenoting the same, or similar structural elements of FIG. 13, anddescriptions thereof are omitted.

An input key-purpose memory region 483 is provided in the communicationmemory 48 of the communication control unit 4 (S1). Next, a descriptionis made of input keys.

Configuration information of the control apparatus contains informationfor indicating whether or not the communication control unit 4 (S1) andthe communication control unit 7 (S2) are connected; and both sorts andsequences of the input devices 9, 10, 11 (1 to n), and the outputdevices 12, 13, 14 (1 to m), which are connected to these communicationcontrol units 4 (S1) and 7 (S2). In the second embodiment of the presentinvention, combinations of such devices among the input devices 9, 10,11 (1 to n), into which data are wanted to be simultaneously inputtedfrom the equipment under control 6, are also added to the configurationinformation. This information is indicated by a combination between aninput key and a device address. When the control apparatus is initiated,the information is written via the control bus 2 (communication channel1) into the input key-purpose memory region 483 of the communicationcontrol unit 4 (S1). Furthermore, among the input keys 93, 103, 113 (1to n) which are provided in the respective input devices 9, 10, 11 (1 ton) via the input/output bus 5 (communication channel 2), statuses ofinput keys of such input devices which are wanted to be entered are setto “opens.” When the control apparatus is activated after the controlapparatus has been set to the above-described statuses, if an inputfreeze signal line 51 added to the input/output bus 5 (communicationchannel 2) becomes a level “H”, then only such an input device that aninput key is under open status among the input buffers 92, 102, 112 (1to n) provided in the respective input devices 9, 10, 11 (1 to n) stopsupdating of data input from the input registers 91, 101, and 111 (1 ton), and also, outputs such a data whose level is kept constant to theinput/output bus 5 (communication channel 2). When the level of theinput freeze signal line 51 becomes a level “L”, the input buffers 92,102, 112 (1 to n) of the input devices where the input keys are underopen statuses also restart the data inputs from the input registers 91,101, 111 (1 to n), and thus, directly output the data from the inputregisters 91, 101, 111 (1 to n) to the input/output bus 5 (communicationchannel 2).

FIG. 14 indicates operation sequences for permitting/stopping dataupdating operations with respect to the input buffers 92, 102, 112 (1 ton) via the control bus 2 (communication channel 1) and the input/outputbus 5 (communication channel 2).

Among data strings and symbols of time instants shown in the drawing,the same names imply the same contents as those shown in FIG. 3 and FIG.6, and descriptions thereof are omitted.

At a time “ti1”, when an input command of the central processing unit 1(CPU) is changed to a level “L”, an input trigger command “R (1, IES)”is transferred as an interrupt at a time instant “tc4” when thecommunication control unit 3 (P0) accepts a communication command.

The input trigger command R (1, IFS) contains a combined input key(IKey) and a device address (Dev) of a device, which are wanted to beinputted. The device address constitutes the n-bit ON/OFF data in thefirst embodiment of FIG. 1; for instance, when the device address isinputted from the input device 1, data of a first bit is transferred as1, whereas when the device address is not inputted from the input device2, data of a second bit is transferred as 0. These data have beenpreviously written as the configuration information into thecommunication memory 48 of the communication control unit 4 (S1).However, every time these data are transferred, the transferred data arecompared with each other, so that reliability can be increased.

The communication control unit 4 (S1) recognizes that an instruction isissued for the own equipment, and transfers an echo “E (1, IFS).”

Also, the communication control unit 4 (S1) sets the input freeze signalline 51 of the input/output bus 5 (communication channel 2) to a levelH. As a result, the input buffers 92, 102, 112 (1 to n) of such inputdevices that input keys are under open statuses stop data input updatingoperation, and output the data kept constant to the input/output bus 5(communication channel 2).

In the second embodiment of FIG. 14, the control apparatus is arrangedas follows: That, in a safety communication layer provided in thecommunication control unit 3 (P0), the input trigger command “R (1,IFS)” is compared with the echo command “E (1, IFS).” Assuming now thatan abnormal condition occurs, an input update command R (1, IFR) (willbe discussed later) is issued, and thus, updating operation of the inputbuffer is restarted.

Thereafter, at time instants t1 and t2, the input data is transferredfrom the communication control unit 4 (S1) to the communication controlunit 3 (P0).

In the second embodiment of FIG. 14, at a time instant t10, the inputdata is again transmitted, and the input data are compared with eachother 2 times in the safety communication layer in order to increase thesafety characteristic of the data. When the input data comparison isaccomphed at a time instant “ti14”, a data input completion signal istransferred to the central processing unit 1 (CPU).

Thereafter, at a time “ti5”, when an input command of the centralprocessing unit 1 (CPU) is changed to a level “H”, an input updatecommand “R (1, IFR)” is transferred as an interrupt at a time instant“tc6” when the communication control unit 3 (P0) accepts a communicationcommand.

The input update command R (1, IFR) contains a device address (Dev) atwhich updating operation of an input buffer is wanted to be restarted.

The communication control unit 4 (S1) recognizes that an instruction isissued for the own equipment, and transfers an echo “E (1, IFS).”

Also, the communication control unit 4 (S1) sets the input freeze signalline 51 of the input/output bus 5 (communication channel 2) to a levelL. As a result, the input buffers 92, 102, 112 (1 to n) of such inputdevices that input keys are under open statuses restart data inputupdating operation, and directly output the data of the input registers91, 101, 111 (1 to n) to the input/output bus 5 (communication channel2).

In accordance with the above-described operation sequences, the inputtrigger command of the central processing unit 1 (CPU) is transferredvia the control bus 2 (communication channel 1) and the input/output bus5 (communication channel 2) to the input unit so as to stop/permit thedata updating operations of the input buffers. As a result, the data canbe inputted at the same time with having a minimum delay from the inputtrigger command.

Also, subsequent to the input updating command R (1, IFR), at a timeinstant “tc7”, the bus diagnosis command R (1, BD) of FIG. 6 istransferred. As a consequence, the input/output bus 5 (communicationchannel 2), and the input devices 9, 10, 11 (1 to n) can be tested anddiagnosed at such a timing that an influence given to the controlperformance becomes the smallest value.

Third Embodiment

FIG. 15 indicates a control apparatus according to a third embodiment ofthe present invention. It should be understood that the same referencenumerals shown in FIG. 5 will be employed as those for denoting thesame, or similar structural elements of FIG. 15, and descriptionsthereof are omitted.

An output key-purpose memory region 786 is provided in the communicationmemory 48 of the communication control unit 7 (S2). Next, a descriptionis made of output keys. In addition to basic configuration informationof the control apparatus, combinations of output devices among theoutput devices 12, 13, 14 (1 to m), which are wanted to be outputted atthe same time to the equipment under control 6, are added to theconfiguration information. This information is indicated by acombination between an output key and a device address. When the controlapparatus is initiated, the information is written via the control bus 2(communication channel 1) into the output key-purpose memory region 786of the communication control unit 7 (S2). Furthermore, among the outputkeys 124, 134, 144 (1 to m) which are provided in the respective outputdevices 12, 13, 14 (1 to m) via the input/output bus 8 (communicationchannel 2), statuses of output keys of such output devices which arewanted to be entered are set to “opens.” When the control apparatus isactivated after the control apparatus has been set to theabove-described statuses, if an output freeze signal line 81 added tothe input/output bus 5 (communication channel 2) becomes a level “H”,then only such an output device that an output key is under open statusamong the output buffers 123, 133, 143 (1 to m) provided in therespective output devices 12, 13, 14 (1 to m) stops updating operationof data output to the output registers 121, 131, 141 (1 to m), and also,outputs such a data whose level is kept constant to the equipment undercontrol 6. It should also be understood that the output buffers 123,133, 143 (1 to m) themselves are continuously updated from the outputdata memory region 783 via the input/output bus 8 (communication channel2). When the level of the data output freeze signal line 81 becomes alevel “L”, the output registers 121, 131, 141 (1 to m) of the outputdevices where the output keys are under open statuses also restart thedata updating operations from the output buffers 123, 133, 143 (1 to m),and thus, directly outputs the data of the output data memory region 783to the equipment under control 6.

FIG. 16 indicates operation sequences for permitting/holding dataupdating with respect to the output buffers 123, 133, 143 (1 to m) viathe control bus 2 (communication channel 1) and the input/output bus 5(communication channel 2).

Among data strings and symbols of time instants shown in the drawing,the same names imply the same contents as those shown in FIG. 3 and FIG.6, and descriptions thereof are omitted.

At a time instant “tq1”, when an output command of the centralprocessing unit 1 (CPU) is changed to a level L, a write protection ofthe communication control unit 3 (P0) via a parallel transfer bus 0(communication channel 0) becomes valid (level H). As a result, writingof data into the relevant memory region within the output data memoryregion 383 of the communication memory 38 can be protected. Next, at atime instant “tc8” when the communication control unit 3 (P0) accepts acommunication command, an output trigger command “R (2, QFS)” istransferred as an interrupt.

The output trigger command R (2, QFS) contains a combined output key(QKey) and a device address (Dev) of a device, which are wanted to besimultaneously outputted. The device address constitutes the m-bitON/OFF data in the first embodiment of FIG. 1; for instance, when thedevice address is inputted from the output device 1, data of a first bitis transferred as 1, whereas when the device address is not inputtedfrom the input device 2, data of a second bit is transferred as 0. Thesedata have been previously written as the configuration information intothe communication memory 78 of the communication control unit 7 (S2).However, every time these data are transferred, the transferred data arecompared with each other, so that reliability can be increased.

The communication control unit 7 (S2) recognizes that an instruction isissued for the own equipment, and transfers an echo “E (2, QFS).”

Also, the communication control unit 7 (S2) sets the output freezesignal line 81 of the input/output bus 8 (communication channel 2) to alevel H. As a result, the output buffers 123, 133, 143 (1 to m) of suchoutput devices that output keys are under open statuses stop data outputupdating operation, and output the data kept constant to the equipmentunder control 6.

In the third embodiment of FIG. 16, a control apparatus is arranged asfollows: That, in a safety communication layer provided in thecommunication control unit 3 (P0), the output trigger command “R (2,QFS)” is compared with the echo command “E (2, QFR).” Assuming now thatan abnormal condition occurs, an output update command R (2, QFR) (willbe discussed later) is issued, and thus, updating of the output bufferis restarted.

Thereafter, at time instant t3 and t4, the output data is transferredfrom the communication control unit 3 (P0) to the communication controlunit 7 (S2).

In the third embodiment of FIG. 14, at a time instant “tq5”, the outputdata is compared with the output echo back so as to increase the safetycharacteristic of the data. When the input/output data comparison isaccomplished, at a time instant “tq4”, an output data completion signalis transferred to the central processing unit 1 (CPU).

Thereafter, at a time instant “tq6”, when an output command of thecentral processing unit 1 (CPU) is changed to a level H, the writeprotection of the communication control unit 3 (P0) is released (namely,level L) at a time instant “tc7.” Also, an output update command “R (2,QFR)” is transferred as an interrupt at a time instant “tc10” when thecommunication control unit 3 (P0) accepts a communication command.

The output update command R (2, QFR) contains a device address (Dev) atwhich updating operation of an output buffer is wanted to be restarted.

The communication control unit 7 (S2) recognizes that an instruction isissued for the own equipment, and transfers an echo “E (2, QFR).”

Also, the communication control unit 7 (S2) sets the output freezesignal line 81 of the input/output bus 8 (communication channel 2) to alevel L. As a result, the communication control unit 7 (S2) restartsoutput updating operations of the output buffers 123, 133, 143 (1 to m)of such output devices that output keys are under open statuses, anddirectly outputs the output data via the output registers 121, 131, 141(1 to m) to the equipment under control 6.

In accordance with the above-described operation sequences, the outputtrigger command of the central processing unit 1 (CPU) is transferredvia the control bus 2 (communication channel 1) and the input/output bus8 (communication channel 2) to the output unit so as to stop/permit theoutput updating operations of the output buffers. As a result, the datacan be outputted at the same time with having a minimum delay from theoutput trigger command.

Also, subsequent to the output updating command R (2, QFR), at a timeinstant “tc11”, the bus diagnosis command R (2, BD) of FIG. 6 istransferred. As a consequence, the input/output bus 8 (communicationchannel 2), and the respective output devices 12, 13, 14 (1 to m) can betested and diagnosed at such a timing that an influence given to thecontrol performance becomes the smallest value. In this case, thereading time instant “t5′” and “t6′” of the output read back succeed thetime instant “tc11.” The result of the output read back constitutes thedata of the preceding time period. However, in accordance with thissystem, programming can be executed by the central processing unit 1(CPU) without paying an attention to the data input timing.

Fourth Embodiment

A control apparatus according to a fourth embodiment of the presentinvention is indicated in FIG. 17. A central processing unit (CPU) 1001is connected via a parallel transfer bus 1000 (communication channel“0”) to a communication control unit 1003 (“P0”). The communicationcontrol unit 1003 (“P0”) transmits and/or receives data via a controlbus 1002 (communication channel “1”) using a serial transfer operationwith respect to a communication control unit 1004 (“S1”), and anothercommunication control unit 1007 (“S2”).

The communication control unit 1004 (“S1”) and an input unit transmitand/or receive input data and a control signal supplied from anequipment under control 1006 via an input/output bus 1005 (communicationchannel “2”) using a parallel transfer operation. The communicationcontrol unit 1007 (“S2”) and an output unit transmit and/or receiveinput data and a control signal to be supplied to the equipment undercontrol 1006 via an input/output bus 1008 (communication channel “2”)using a parallel transfer operation.

The input unit is constituted by “n” pieces of input devices 1009, 1010,and 1011 (1 to n). The respective input devices transmit and/or receiveinput data from the equipment under control 1006 via the input/outputbus 1005 (communication channel 2) with respect to the communicationcontrol unit 1004 (S1). Similarly, the output unit is constituted by “m”pieces of output devices 1012, 1013, and 1014 (1 to m). The respectiveoutput devices transmit and/or receive output data to the equipmentunder control 1006 via the input/output bus 1008 (communication channel2) with respect to the communication control unit 1007 (S2).

Both the communication control unit 1003 (P0) and a GPS (GlobalPositioning System) unit 1015 transmit/receive a reference time instantvia a reference time instant signal 1016.

FIG. 18 indicates a path of data transmitted/received between thecommunication control unit 1003 (P0) and the communication control units1004 (S1) and 1007 (S2) via the control bus 1002 (communication channel1) using the serial transfer operation. With respect to a communicationmemory 1038 provided in the communication control unit 1003 (P0),regions used for a sequence number-purpose memory 1381, an inputdata-purpose memory 1382, an output data-purpose memory 1383, and a readback data-purpose memory 1344 are allocated. Data stored in thecommunication memory 1038 is parallel/serial-converted by acommunication control circuit 1039, and then, parallel/serial-converteddata is transferred via the control bus 1002 (communication channel 1)between communication memories 1048 and 1078 of the communicationcontrol units 1004 (S1) and 1007 (S2).

With respect to the communication memory 1048 employed in thecommunication control unit 1004 (S1), regions used for a sequencenumber-purpose memory 1481 and an input data-purpose memory 1482 areallocated. Data of the input data-purpose memory 1482 within thecommunication memory 1048 is parallel/serial-converted by acommunication control circuit 1049, and then, theparallel/serial-converted data is mapped to the input data-purposememory region 1382 of the communication memory 1038 of the communicationcontrol unit 1003 (P0) via the control bus 1002 (communication channel1).

With respect to the communication memory 1078 provided in thecommunication control unit 1007 (S2), regions used for a sequencenumber-purpose memory 1781, an output data-purpose memory 1781, a readback data-purpose memory 1784, and a temporary holding memory 1785 areallocated. Data stored in the output data-purpose memory region 1383 ofthe communication memory 1038 of the communication control device 1003(P0) is parallel/serial-converted by the communication control circuit1079, and then, the parallel/serial-converted data is transferred viathe control bus 1002 (communication line 1) to the temporary holdingmemory 1785 of the communication memory 1078. Data stored in thetemporary holding memory 1785 is transferred to the output data-purposememory 1783 after such a confirmation is made that a communicationbetween the communication control units 1003 (P0) and 1007 (S2) isnormal. Data stored in the read back data-purpose memory 1784 istransferred to the read back-purpose memory 1384 of the communicationcontrol unit 1003 (P0).

FIG. 19 indicates a data communication operation sequence executed amongthe communication control units 1003 (P0), 1004 (S1), and 1007 (S2) viathe control bus 1002 (communication channel 1).

At a time “t1”, an input request “IR (1, N)” is outputted from thecommunication control unit 1003 (P0) to the communication control unit1004 (S1) to the control bus 1002 (communication channel 1).

The input request IR (1, N) is made of a data string as to a send key(SendKey=0) corresponding to a sender number 0; a receive key(Rcv.Key=1) corresponding to a receiver number 1; a sequence number(Seq.No.=N) used to confirm a transfer data sequence; input deviceinformation (Dev.Adr.) of a transfer destination from the communicationcontrol unit 1004 (S1); and an input data size (DataSize). In addition,both a start flag and an end flag which are commonly used even in anytransfer data are added to a head portion and a tail portion of a datastring. However, for the sake of simplicity, indications of these flagsare omitted. In this case, the input device information (Dev.Adr.)constitutes n-bit ON/OFF data in the first embodiment shown in FIG. 14.For instance, when the input device information is inputted from theinput device 1001, the n-bit ON/OFF data is transferred while first bitdata is set to “1”, whereas when the input device information is notinputted from the input device 1002, the n-bit ON/OFF data istransferred while second bit data is set to “0.”

The communication control unit 1004 (S1) recognizes that a request isissued for the own equipment based upon the receive key (Rev.Key=1) ofthe input request IR (1, N), and then, outputs an input request echo IE(I, N) to the control bus 1002 (communication line 1).

The input request echo IE (1, N) is constituted by a data string as toan input request echo command (IE), a send key (SendKey=1) correspondsto a sender number 1, a receive key (Rcv.Key=0) corresponding to areceiver number 0, and a sequence number (Seq.No.=N) used to confirm atransfer data sequence.

The communication control unit 1003 (P0) confirms that the input requestIR (1, N) has been transferred to the communication control unit 1004(S1) under normal condition by checking that the send key and thereceive key of the input request echo IE (1, N) are reversed to those ofthe input request IR (1, N), and the sequence number (Seq.No.=N) thereofis not changed.

As previously explained, the reversed send key and the reversed receivekey are used in order to monitor a camouflage (masquerade) of acommunication. Also, a time out of a transfer operation is monitored bya communication timer 1 which is operated by sending the input requestIR (1, N) and receiving the input request echo IE (1, N).

At a time instant “t2”, an input access request ID (1, N) from thecommunication control unit 1003 (P0) to the communication control unit1004 (S1) is outputted to the control bus 1002 (communication channel1).

The input access request ID (1, N) is constituted by a data string as toan input request echo command (IA), a send key (SendKey=0) correspondsto a sender number 0, a receive key (Rcv.Key=1) corresponding to areceiver number 1, and a sequence number (Seq.No=N) used to confirm atransfer data sequence.

The communication control unit 1004 (S1) recognizes that a request isissued for the own equipment based upon the receive key (Rcv.Key=1) ofthe input access request ID (1, N), and outputs an input access data IA(1, N) read out from the input data-purpose memory 1482 to the controlbus 1002 (communication channel 1).

The input access data IA (1, N) is constituted by such a data string.That is, the data string is made by an input access request command(IA), a send key (SendKey=1) corresponding to a sender number 1, areceive key (Rcv.Key=0) corresponding to a receiver number 0, a sequencenumber (Seq.No.=N) for confirming a transfer data sequence, input deviceinformation (Dev.Adr.) and an input data size (DataSize) equal to theinput request IR (1, N), and finally, input data (InputData).

The communication control unit 1003 (P0) confirms the send key and thereceive key, the sequence number (Seq.No.=N), the input deviceinformation (Dev.Adr.), the input data size (DataSize) of the inputaccess data IA (1, N).

When a confirmation result is normal, the input data (InputData) iswritten in the input data-purpose memory 11382 employed in thecommunication control unit 1003 (P0). The sequence number is counted upto become (Seq.No.=N+1). The central processing unit 1001 (CPU) can readthe input data from the input data-purpose memory 1382 at timingcontrolled by a program.

During the above-described process operation, the communication timer 1is operated based upon the input access request ID (1, N) and the inputaccess request command IA (1, N). Also, the communication timer 2monitors a time out of the input communication by sending the inputrequest IR (1, N) and by receiving the input access data IA (1, N).

At a time instant “t3”, an output request QR (2, N+1) from thecommunication control unit 1003 (P0) to the communication control unit1007 (S2) is outputted to the control bus 1002 (communication channel1).

The output request QR (2, N+1) is constituted by such a data string asto an output request command (QR), a send key (SendKey=0) correspondingto a sender number 0, a receive key (Rcv.Key=2) corresponding to areceiver number 2, a sequence number (Seq.No.=N+1), output deviceinformation (Dev.Adr.) of a transfer destination from the communicationcontrol unit 1007 (S1), an output data size (DataSize), and output data(OutputData). The output data (OutputData) is written from the outputdata-purpose memory 1383.

In this case, the output device information (Dev.Adr.) constitutes them-bit ON/OFF data in the fourth embodiment of FIG. 17.

The communication control unit 1007 (S2) recognizes that a request forthe own equipment is issued based upon the receive key (Rcv.Key=2) ofthe output request QR (2, N+1), and writes the output data (OutputData)to the temporary holding memory 1785 provided in the communicationcontrol unit 1007 (S2). Also, the communication control unit 1007 (S2)outputs an output request echo QE (2, N+1) to the control bus 1002(communication channel 1).

The output request echo QE (2, N+1) is constituted by such a data stringas to an output request echo command (QE), a send key (SendKey=2), areceive key (Rcv.Key=0), and a sequence number (Seq.No.=N+1).

The communication control unit 1003 (P0) confirms that the outputrequest QR (2, N+1) has been normally transferred to the communicationcontrol unit 1007 (S2) based upon the output request QR (2, N+1), thesend key and the receive key of the output request echo QE (2, N+1), andthe sequence number (Seq.No.=N+1). The communication timer 1 is operatedbased upon the output request QR (2, N+1) and the output request echo QE(2, N+1).

At a time instant “t4”, an output access request QD (2, N+1) from thecommunication control unit 1003 (P0) to the communication control unit1007 (S2) is outputted to the control bus 1002 (communication channel1).

The output access request QD (2, N+1) is constituted by such a datastring as to an output access request command (QA), a send key(SendKey=0) corresponding to a sender number 0, a receive key(Rcv.Key=2) corresponding to a receiver number 2, a sequence number(Seq.No.=N+1) used to confirm a transfer data sequence.

The communication control unit 1007 (S2) recognizes that an outputrequest for the own equipment is issued based upon the receive key(Rcv.Key=2) of the output access request QD (2, N+1) and the sequencenumber (Seq.No.=N+1), and then, outputs the data stored in the temporaryholding memory 1785 provided in the communication control unit 1007 (S2)to the output data-purpose memory 1783. Also, the communication controlunit 1007 (S2) outputs the output access request data QA (2, N+1) to thecontrol bus 1002 (communication channel 1).

The output request echo QA (2, N+1) is constituted by such a data stringas to an output access request command (QA), a send key (SendKey=2), areceive key (Rcv.Key=0), and a sequence number (Seq.No.=N+1), an outputaccess request QA (2, N+1), output device information (Dev.Adr.), anoutput data size (DataSize), and finally, an output echo back(OutputEchoback) written from the temporary holding memory 1785.

The communication control unit 1003 (P0) confirms the send key and thereceive key of the output access data QA (2, N+1), the sequence number(Seq.No.=N+1), the output device information (Dev.Adr.), and the outputdata size (DataSize). When a confirmation result becomes normal, thesequence number is counted up (Seq.No.=N+2).

During the above-described process operation, the communication timer 1is operated based upon the output access request QD (2, N+1) and theoutput access data QA (2, N+1). Also, the communication timer 2 monitorsa time out of the output communication by sending the output request QR(2, N+1) and by receiving the output access data QA (1, N+1).

In the fourth embodiment of FIG. 17, since the output echo back(OutputEchoback) is added to the output access data QA (2, N+1), thecommunication control unit 1003 (P0) can compare the added data with theoutput data (OutputData), so that the communication control unit 1003(P0) can confirm that the output data has been transferred under thenormal condition.

A time period defined from a time instant “t5” to a time instant “t7”indicates an input communication in the case that an output read backfunction is provided with a portion, or all of the output devices 1012,1013, 1014 (1 to m) of the output unit.

A difference between the above-described input communication of the timeperiod from the time instant “t1” to the time instant “t3” and thisinput communication of the time period from the time instant “t5” to thetime instant “t7” is given as follows in addition to the sequencenumbers: That is, the counter party of the communication control unit1003 (P0) is the communication control unit 1007 (S2) with respect tothe communication control unit 1004 (S1); and the input deviceinformation (Dev.Adr.) is the m-bit ON/OFF data with respect to then-bit ON/OFF data; and the output read back data (OutputEchoback)corresponds to the input data (InputData). Also, the m-bit data of theinput device information (Dev.Adr.) indicates whether or not the outputread back data of the output devices 1012, 1013, 1014 (1 to m) arepresent. Other aspects of the input communication are identical to thoseof the input communication defined from the time instant t1 to the timeinstant t3. Concrete data strings are given as follows:

With execution of the above-described communication operations, the datacommunication among the communication control units 1003 (P0), 1004(S1), and 1007 (S2) via the control bus 1002 (communication channel 1)is circulatedly carried out, and then, at the time instant t7, the sameoperation as that of the time instant t1 is commenced. It should also benoted that this communication operation is the same as that of the timeinstant t1 except that a sequence number becomes (Seq.No.=N+3). Aspreviously explained, the data transferring operation via the controlbus 1002 (communication channel 1) corresponds to the memorytransferring operation executed in a predetermined periodic operationsequence, and the operation sequence from the time instant t1 to thetime instant t6 is not reversed, but also is not omitted. As a result,the sequential control of the data strings is not required, so that idletimes between the data strings can be minimized, and the transferefficiency can be increased.

It should be understood that in the reset timing (t1, t2, - - - , t6) ofthe communication timer 1, other communication commands may bealternatively interrupted. Also, in this alternative case, an operationsequence of a memory transferring operation is not reversed, but also isnot omitted except that a completion of the interrupted communicationcommand is merely waited.

FIG. 20 indicates a path of data transmitted/received between thecommunication control unit 1004 (S1) and an input unit via theinput/output bus 1005 (communication channel 2). Each of “n” pieces ofthe input devices 1009, 1010, 1011 (1 to n) which constitute the inputunit is equipped with an input register 1091, another input register1101, and a further input register 1111 respectively, while measurementdata from the equipment under control 1006 is written into the inputregisters 1091, 1101, 1111 in either timing or a time period incorrespondence with structures of these input devices 1091, 1101, 1111.The measurement data stored in the input registers 1091, 1101, 1111 aretransferred in a periodic manner via the input/output bus 1005(communication channel 2) to the input data-purpose memory region 1482of the communication memory 1048 of the communication control unit 1004(S1).

FIG. 21 indicates a path of data transmitted/received between thecommunication control unit 1007 (S2) and an output unit via theinput/output bus 1008 (communication channel 2). Each of “m” pieces ofthe output devices 1012, 1013, 1014 (1 to m) which constitute the outputunit is equipped with an output register 1121, another output register1131, and a further output register 1141 respectively, while data isoutputted to the equipment under control 1006 in either timing or a timeperiod in correspondence with structures of the output devices 1012,1013, 1014 (1 to m). Data stored in the output data-purpose memoryregion 1783 of the communication memory 1078 of the communicationcontrol unit 1007 (S2) is transferred via the input/output bus 1008(communication channel 2) to the output registers 1121, 1131, 1141 in aperiodic manner. On the other hand, in the fourth embodiment of FIG. 5,the respective output devices 1012, 1013, 1014 (1 to m) have beenequipped with the functions capable of reading back outputs to theequipment under control 1006. The read back results are written in theread back registers 1122, 1132, 1142, and are transferred via theinput/output bus 1008 (communication channel 2) to the read backdata-purpose memory region 1784 of the communication memory 1078 of thecommunication control unit 1007 (S2) in a periodic manner.

As indicated in FIG. 18, FIG. 19, FIG. 20, and FIG. 21, any of thecontrol bus 1002 (communication channel 1), the input/output bus 1005(communication channel 2), and the input/output bus 1008 (communicationchannel 2) have been made of such a basic structure that the specificmemory transferring operations can be independently carried out.

Referring now to FIG. 22, FIG. 23, and FIG. 24, a description is made ofa method for capable of realizing that a time stamp is added to inputdata in the above-described basic arrangement, corresponding to thefourth embodiment of the present invention.

FIG. 22 indicates an internal arrangement of the communication controlunit 1003 (P0). A reference time instant is transmitted/received fromthe GPS receiver 1015 to the communication control unit 1003 (P0) via areference time instant signal 1016. The reference time instant signal1016 corresponds to such a signal whose bit is correctly inverted every1 second. A time counter 1310 is such a counter which counts up a countvalue every 1 millisecond. The reference time instant signal 1016 isinputted to the time counter 1310, and is used in order to correct atime instant. Concretely speaking, in response to change the timeinstant signal 1016, digits of the time counter 1310, which are smallerthan 1 second, are rounded off, or discarded.

Time stamp setting information 1385 indicates such an informationrelated to time stamps as to one of the input devices 1009, 1010, 1111(1 to n), and one of the output devices 1012, 1013, 1014 (1 to m). Thetime stamp setting information 1385 is constituted by a station number13851, a device number 13852, a time stamp validity 13853, adigital/analog sort 13854, an event sort 13855, a time stamp pointer13856, preceding data 13857, and a preceding data valid bit 13858.

The station number 13851 corresponds to such a station number in thecontrol bus 1002 of a communication control unit to which the relevantdevice has been connected via the input/output bus 1008 (communicationchannel 2). The device number 13852 corresponds to such a device numberin the input/output bus 1008 to which the relevant device has beenconnected. The time stamp validity 13853 corresponds to such a bit forselecting whether or not a time stamp is formed. The digital/analog sort13854 indicates that input/output data of the input devices 1009, 1010,1011 (1 to n), and of the output devices 1012, 1013, 1014 (1 to m) areeither digital data or analog data. The event sort 13855 corresponds toa condition under which time stamp data is formed. In a digital signal,an event is selected from “0→1”, “1→0”, or “both 0→1 and 1→0” In ananalog signal, both boundary value data and an event are selected. Thisevent is selected from “when input data is increased to exceed boundaryvalue”; “when input data is decreased to exceed boundary value”; or“when input data exceeds boundary value irrespective ofincreased/decreased input data.” The time stamp pointer 13856 representssuch an address of the time stamp memory 1387 where time stamps havebeen stored, at which the latest time stamp has been stored. Thepreceding data 13857 implies that in order to save such a preceding datawhich is compared with the latest data when an occurrence of an event isjudged, when data is inputted, the latest data is written in thepreceding data when the event is judged. The preceding data valid bit13858 indicates that the preceding data is valid, or invalid.

When a control apparatus is initiated, the central processing unit 1001(CPU) sets the time stamp device setting information 1385.

The input time instant buffer 1386 corresponds to such a buffer which isemployed so as to temporarily save an input time instant.

The time stamp memory 1387 corresponds to such a region which forms atime stamp and then stores thereinto the formed time stamp. The timestamp memory 1387 is constituted by an invalid bit 13871, data 13872,and a time instant 13873 every input signal and every output signal. Thevalid bit 13871 indicates that the time stamp is valid, or invalid. Thedata 13872 represents such a data when an event set by the event sort13855 occurs. When an input signal is produced, the data 13872 indicatesinput data, whereas when an output signal is produced, the data 13872indicates read back data. The time instant 13873 indicates such a timeinstant when an event set by the event sort 13855 happens to occur.

The central processing unit 1001 (CPU) can read out both a time instantwhen the latest event occurs and another time instant when an eventpreceding to the latest event occurs from the time stamp memory 1387indicated by the time stamp pointer 13856. The central processing unit1001 (CPU) writes “invalid statuses” into the valid bit 13871 and thepreceding data valid bit 13858 before input/output data communication iscarried out.

A detailed structure of an input key-purpose memory region 1388 will benow described with reference to FIG. 23.

FIG. 23 represents a communication structure of a peripheral region ofthe input/output bus 1008 (communication channel 2). It should beunderstood that the same reference numerals shown in FIG. 4 will beemployed as those for denoting the same, or similar structural elementsof FIG. 20, and descriptions thereof are omitted.

An input key-purpose memory region 1483 is provided in the communicationmemory 1048 of the communication control unit 1004 (S1). Next, adescription is made of input keys.

Configuration information of the control apparatus contains informationfor indicating whether or not the communication control unit 1004 (S1)and the communication control unit 1007 (S2) are connected; and bothsorts and sequences of the input devices 1009, 1010, 1011 (1 to n), andthe output devices 1012, 1013, 1014 (1 to m), which are connected tothese communication control units 1004 (S1) and 1007 (S2). In the fourthembodiment of the present invention, combinations of such devices amongthe input devices 1009, 1010, 1011 (1 to n), into which time stamps arewanted to be added from the equipment under control 1006, are also addedto the configuration information. This information is indicated by acombination between an input key and a device address. When the controlapparatus is initiated, the information is written via the control bus1002 (communication channel 1) into the input key-purpose memory region1483 of the communication control unit 1004 (S1). Furthermore, among theinput keys 1093, 1103,1113 (1 to n) which are provided in the respectiveinput devices 1009, 1010, 1011 (1 to n) via the input/output bus 1005(communication channel 2), statuses of input keys of such input devicesto which the time stamps are wanted to be added are set to “opens.” Whenthe control apparatus is activated after the control apparatus has beenset to the above-described statuses, if an input freeze signal line 1051added to the input/output bus 1005 (communication channel 2) becomes alevel “H”, then only such an input device that an input key is underopen status among the input buffers 1092, 1102, 1112 (1 to n) providedin the respective input devices 1009, 1010, 1011 (1 to n) stops updatingof data input from the input registers 1091, 1101, and 1111 (1 to n),and also, outputs such a data whose level is kept constant to theinput/output bus 1005 (communication channel 2). When the level of theinput freeze signal line 1051 becomes a level “L”, the input buffers1092, 1102, 1112 (1 to n) of the input devices where the input keys areunder open statuses also restart the data inputs from the inputregisters 1091, 1101, 1111 (1 to n), and thus, directly output the datafrom the input registers 1091, 1101, 1111 (1 to n) to the input/outputbus 1005 (communication channel 2).

FIG. 24 indicates operation sequences for permitting/stopping dataupdating operations with respect to the input buffers 1092, 1102, 1112(1 to n) via the control bus 1002 (communication channel 1) and theinput/output bus 1005 (communication channel 2).

Among data strings and symbols of time instants shown in the drawing,the same names imply the same contents as those shown in FIG. 19 anddescriptions thereof are omitted.

At a time “ti1”, when an input command of the central processing unit1001 (CPU) is changed to a level “L”, an input trigger command “R (1,IFS)” is transferred as an interrupt at a time instant “tc4” when thecommunication control unit 1003 (P0) accepts a communication command.

The input trigger command R (1, IFS) contains a combined input key(IKey) and a device address (Dev) of a device, to which the time stampsare wanted to be inputted. The device address constitutes the n-bitON/OFF data in the fourth embodiment of FIG. 17; for instance, when thedevice address is inputted from the input device 1, data of a first bitis transferred as 1, whereas when the device address is not inputtedfrom the input device 2, data of a second bit is transferred as 0. Thesedata have been previously written as the configuration information intothe communication memory 1048 of the communication control unit 1004(S1). However, every time these data are transferred, the transferreddata are compared with each other, so that reliability can be increased.

In order to save such a present time instant when the input freezingoperation is commenced in the input device after the transmission of theinput trigger command R (1, IFS) is accomplished (namely, time instant“ti2 a”), the communication control circuit 1039 stores the present time(“Tn”) which has been stored in the time instant counter 1310 into theinput time instant buffer 1386.

The communication control unit 1004 (S1) recognizes that an instructionis issued for the own equipment, and transfers an echo “E (1, IFS).”

Also, the communication control unit 1004 (S1) sets the input freezesignal line 1051 of the input/output bus 1005 (communication channel 2)to a level H. As a result, the input buffers 1092, 1102, 1112 (1 to n)of such input devices that input keys are under open statuses stop datainput updating operation, and output the data kept constant to theinput/output bus 1005 (communication channel 2).

In the fourth embodiment of FIG. 24, a control apparatus is arranged asfollows: That, in a safety communication layer provided in thecommunication control unit 1003 (P0), the input trigger command “R (1,IFS)” is compared with the echo command “E (1, IFS).” Assuming now thatan abnormal condition occurs, an input update command R (1, IFR) (willbe discussed later) is issued, and thus, updating operation of the inputbuffer is restarted.

Thereafter, at time instants t1 and t2, the input data is transferredfrom the communication control unit 1004 (S1) to the communicationcontrol unit 1003 (P0).

In the fourth embodiment of FIG. 24, at a time instant t10, the inputdata is again transmitted, and the input data are compared with eachother 2 times in the safety communication layer in order to increase thesafety characteristic of the data.

If the input data are coincident with each other at a time instant“ti4”, then the central processing unit 1001 (CPU) judges whether or nota time stamp is produced with reference to the time stamp device settinginformation 1385.

In the case that the time stamp is produced, the central processing unit1001 (CPU) compares the digital/analog sort 13854, the event sort 13855with the preceding data 13857 and the input data with reference to thetime stamp setting information 1385 so as to judge whether or not anevent happens to occur.

In the case of a digital device, if the below-mentioned equations can beestablished, then the central processing unit 1001 (CPU) judges that theevent occurs. It is so assumed that the preceding data 13857=d0, and theinput data=d1.

In the case that the event sort 13855=“0→1”,(d0=0)·(d1=1)  (Equation 1)

In the case that the event sort 13855=“1→0”,(d0=1)·(d1=0)  (Equation 2)

In the case that the event sort 13855=“both 0→1 and 1→0”,(d0=0)·(d1=1)+(d0=1)·(d1=0)  (Equation 3)

In the case of an analog device, if the below-mentioned equations can beestablished, then the central processing unit 1001 (CPU) judges that theevent occurs. It is so assumed that the preceding data 13857=d0, theinput data=d1, and a boundary value=b.

In the case that the event sort 13855=“when input data is increased toexceed boundary value”,(d0≦b)·(d1>b)  (Equation 4)

In the case that the even sort 13855=“when input data is decreased toexceed boundary value”,(d0≧b)·(d1<b)  (Equation 5)

In the case that the event sort 13855=“when input data exceeds boundaryvalue irrespective of increased/decreased input data”,(d0≦b)·(d1>b)+(d0≧b)·(d1<b)  (Equation 6)

When the central processing unit 1001 (CPU) judges that the eventoccurs, the time stamp is written in the time stamp memory 1387. If avalid bit 13871 of the time stamp memory 1387 indicated by a time stamppointer 13856 is valid, then the central processing unit 1001 (CPU) addsthe time stamp to the valid bit in order to be moved to a next timestamp storage address, and then writes the added valid bit into the timestamp pointer 13856. The central processing unit 1001 (CPU) writes“valid” in the valid bit 13871 of the time stamp memory 1387 indicatedby the time stamp pointer 13856, writes input data in the data 13872,and writes such a time instant value read out from the input timeinstant buffer 1386 in the time instant 13873.

The central processing unit 1001 (CPU) writes the input data in thepreceding data 13857 and “valid” in the preceding data valid bit 13858irrespective of such a fact that the event occurs.

When a series of the above-described process operations is accomplished,a data input completion signal is transferred to the central processingunit 1001 (CPU).

Thereafter, at a time “ti5”, when an input command of the centralprocessing unit 1001 (CPU) is changed to a level “H”, an input updatecommand “R (1, IFR)” is transferred as an interrupt at a time instant“tc6” when the communication control unit 1003 (P0) accepts acommunication command.

The input update command R (1, IFR) contains a device address (Dev) atwhich updating operation of an input buffer is wanted to be restarted.

The communication control unit 1004 (S1) recognizes that an instructionis issued for the own equipment, and transfers an echo “E (1, IFS).”

Also, the communication control unit 1004 (S1) sets the input freezesignal line 1051 of the input/output bus 1005 (communication channel 2)to a level L. As a result, the input buffers 1092, 1102, 1112 (1 to n)of such input devices that input keys are under open statuses restartdata input updating operation, and directly output the data of the inputregisters 1091,1101, 1111 (1 to n) to the input/output bus 1005(communication channel 2).

In accordance with the above-described operation sequences, the inputtrigger command of the central processing unit 1001 (CPU) is transferredvia the control bus 1002 (communication channel 1) and the input/outputbus 1005 (communication channel 2) to the input unit so as tostop/permit the data updating operations of the input buffers. Thecommunication control unit 1003 (P0) judges that the event occurs in theinput device, and writes in the time stamp memory 1387, so that thecentral processing unit 1001 (CPU) can establish a relationship betweenthe input data and the time stamp.

Fifth Embodiment

Referring now to FIG. 22, FIG. 15, and FIG. 26, a description is made ofa method capable of realizing that a time stamp is added to read backdata corresponding to output data, according to a fifth embodiment ofthe present invention.

FIG. 22 represents an internal arrangement of the communication controlunit 1003 (P0). It should be noted that the same contents as explainedin FIG. 22 are omitted.

An output time instant buffer 1389 corresponds to a buffer whichtemporarily saves an output time instant.

A detailed content of the output key-purpose memory region 13810 will bedescribed with reference to FIG. 25.

FIG. 25 shows a communication structure of a peripheral region of theinput/output bus 1008 (communication channel 2). It should also beunderstood that the same reference numerals shown in FIG. 21 will beemployed as those for denoting the same structural elements of FIG. 25,and descriptions thereof are omitted.

An output key-purpose memory region 1786 is provided in thecommunication memory 1048 of the communication control unit 1007 (S2).Next, a description is made of output keys. In addition to basicconfiguration information of the control apparatus, combinations ofoutput devices among the output devices 1012, 1013, 1014 (1 to m), towhich time stamps are wanted to be added to the equipment under control1006, are also added to the configuration information. This informationis indicated by a combination between an output key and a deviceaddress. When the control apparatus is initiated, the information iswritten via the control bus 1002 (communication channel 1) into theoutput key-purpose memory region 1786 of the communication control unit1007 (S2). Furthermore, among the output keys 1124, 1134, 1144 (1 to m)which are provided in the respective output devices 1012, 1013, 1014 (1to m) via the input/output bus 1008 (communication channel 2), statusesof output keys of such output devices to which the time stamps arewanted to be added are set to “opens.” When the control apparatus isactivated after the control apparatus has been set to theabove-described statuses, if an output freeze signal line 1081 added tothe input/output bus 1005 (communication channel 2) becomes a level “H”,then only such an output device that an output key is under open statusamong the output buffers 1123, 1133, 1143 (1 to m) provided in therespective output devices 1012, 1013, 1014 (1 to m) stops updatingoperation of data output to the output registers 1121, 1131, 1141 (1 tom), and also, outputs such a data whose level is kept constant to theequipment under control 1006. It should also be understood that theoutput buffers 1123, 1133, 1143 (1 to m) themselves are continuouslyupdated from the output data memory region 1783 via the input/output bus1008 (communication channel 2). When the level of the data output freezesignal line 1081 becomes a level “L”, the output registers 1121, 1131,1141 (1 to m) of the output devices where the output keys are under openstatuses also restart the data updating operations from the outputbuffers 1123, 1133, 1143 (1 to m), and thus, directly outputs the dataof the output data memory region 1783 to the equipment under control1006.

FIG. 26 indicates operation sequences for permitting/holding dataupdating with respect to the output buffers 1123, 1133, 1143 (1 to m)via the control bus 1002 (communication channel 1) and the input/outputbus 1008 (communication channel 2).

Among data strings and symbols of time instants shown in the drawing,the same names imply the same contents as those shown in FIG. 19, anddescriptions thereof are omitted.

At a time instant “tq1”, when an output command of the centralprocessing unit 1001 (CPU) is changed to a level L, a write protectionof the communication control unit 1003 (P0) via a parallel transfer bus0 (communication channel 0) becomes valid (level H). As a result,writing of data into the relevant memory region within the output datamemory region 1383 of the communication memory 1038 can be protected.Next, at a time instant “tc8” when the communication control unit 1003(P0) accepts a communication command, an output trigger command “R (2,QFS)” is transferred as an interrupt.

The output trigger command R (2, QFS) contains a combined output key(QKey) and a device address (Dev) of a device, which are wanted to besimultaneously outputted. The device address constitutes the m-bitON/OFF data in the third embodiment of FIG. 17; for instance, when thedevice address is inputted from the output device 1001, data of a firstbit is transferred as 1, whereas when the device address is not inputtedfrom the input device 1002, data of a second bit is transferred as 0.These data have been previously written as the configuration informationinto the communication memory 1078 of the communication control unit1007 (S2). However, every time these data are transferred, thetransferred data are compared with each other, so that reliability canbe increased.

The communication control unit 1007 (S2) recognizes that an instructionis issued for the own equipment, and transfers an echo “E (2, QFS).”

Also, the communication control unit 1007 (S2) sets the output freezesignal line 1081 of the input/output bus 1008 (communication channel 2)to a level H. As a result, the output buffers 1123, 1133, 1143 (1 to m)of such output devices that output keys are under open statuses stopdata output updating operation, and output the data kept constant to theequipment under control 1006.

In the fifth embodiment of FIG. 26, the control equipment is arranged asfollows: That, in a safety communication layer provided in thecommunication control unit 1003 (P0), the output trigger command “R (2,QFS)” is compared with the echo command “E (2, QFR).” Assuming now thatan abnormal condition occurs, an output update command R (2, QFR) (willbe discussed later) is issued, and thus, updating of the output bufferis restarted.

Thereafter, at time instant t3 and t4, the output data is transferredfrom the communication control unit 1003 (P0) to the communicationcontrol unit 1007 (S2).

In the fifth embodiment of FIG. 26, at a time instant “tq5”, the outputdata is compared with the output echo back so as to increase the safetycharacteristic of the data. When the input/output data comparison isaccomplished, at a time instant “tq4”, an output data completion signalis transferred to the central processing unit 1001 (CPU).

Thereafter, at a time instant “tq6”, when an output command of thecentral processing unit 1001 (CPU) is changed to a level H, the writeprotection of the communication control unit 1003 (P0) is released(namely, level L) at a time instant “tc7.” Also, an output updatecommand “R (2, QFR)” is transferred as an interrupt at a time instant“tc10” when the communication control unit 1003 (P0) accepts acommunication command.

The output update command R (2, QFR) contains a device address (Dev) atwhich updating operation of an output buffer is wanted to be restarted.

In order to save such a present time instant when the output updatingoperation is commenced in the input device after the transmission of theinput trigger command R (2, QFR) is accomplished (namely, time instant“tq8 a”), the communication control circuit 1039 stores the present time(“Tn”) which has been stored in the time instant counter 1310 into theoutput time instant buffer 1389.

The communication control unit 1007 (S2) recognizes that an instructionis issued for the own equipment, and transfers an echo “E (2, QFR).”

Also, the communication control unit 1007 (S2) sets the output freezesignal line 1081 of the input/output bus 1005 (communication channel 2)to a level H. As a result, the output buffers 1123, 1133, 11432 (1 to m)of such output devices that output keys are under open statuses restartdata output updating operation, and directly output the updated data tothe equipment under control 1006 via the output register input buffers1121, 1131, 1141 (1 to m).

When the command comparing operation is accomplished at a time instant“tq9”, the communication control unit 1007 (S2) transfers an outputupdating command completion signal to the central processing unit 1001(CPU).

Thereafter, when the read back command of the central processing unit1001 (CPU) is changed into a level “L”, at a time instant “tq10”, thesafety communication layer of the communication control unit 1003 (P0)waits until the output read back data is received.

Thereafter, when the output read back is received, the communicationcontrol unit 1003 (P0) compares the read back data with the time stampdevice setting information at a time instant “tq11.” If thecommunication control unit 1003 (P0) judges that an event occurs, then atime stamp is written in the time stamp memory 1387. If a valid bit13871 of the time stamp memory 1387 indicated by a time stamp pointer13856 is valid, then the central processing unit 1001 (CPU) adds thetime stamp to the valid bit in order to be moved to a next time stampstorage address, and then writes the added valid bit into the time stamppointer 13856. The central processing unit 1001 (CPU) writes “valid” inthe valid bit 13871 of the time stamp memory 1387 indicated by the timestamp pointer 13856, writes read back data in the data 13872, and writessuch a time instant value read out from the output time instant buffer1389 in the time instant 13873.

The central processing unit 1001 (CPU) writes the read back data in thepreceding data 13857 and “valid” in the preceding data valid bit 13858irrespective of such a fact that the event occurs.

When a series of the above-described process operations is accomplished,a read back data input completion signal is transferred to the centralprocessing unit 1001 (CPU).

Thereafter, at a time “tq12”, when an output command of the centralprocessing unit 1001 (CPU) is changed to a level “H”, at a time instant“tq13”, the write protection of the communication control unit 1003 (P0)is released (namely, level “L”).

In accordance with the above-described operation sequences, the outputtrigger command of the central processing unit 1001 (CPU) is transferredvia the control bus 1002 (communication channel 1) and the input/outputbus 1008 (communication channel 2) to the output unit so as tostop/permit the output data updating operations of the output buffers.The communication control unit 1003 (P0) judges that the event occurs inthe output device, and writes in the time stamp memory 1387, so that thecentral processing unit 1001 can establish a relationship between theoutput data and the time stamp.

Sixth Embodiment

Referring now to FIG. 27, FIG. 28, and FIG. 29, a description is made ofa method for capable of realizing that a time stamp is added to inputdata, according to a sixth embodiment of the present invention.

FIG. 22 indicates an internal arrangement of the communication controlunit 1003 (P0). It should be understood that the same reference numeralsshown in FIG. 22 will be employed as those for denoting the same, orsimilar structural elements of FIG. 27 to FIG. 29, and descriptionsthereof are omitted. A different structural point of this sixthembodiment according to the present invention from the above-describedfifth embodiment is given as follows: That is, an input time instantbuffer 1486 is such a buffer which temporarily saves an input timeinstant received via the control bus 1002 (communication channel 1).Also, an output time instant buffer 1489 is such a buffer whichtemporarily save an output time instant received via the control bus1002 (communication channel 1).

FIG. 27 shows a time chart for describing a time instant synchronizingmethod executed in the communication control unit 1003 (P0), thecommunication control unit 1004 (S1), and the communication control unit1007 (S2) via the control bus 1002 (communication channel 1). Thecommunication control unit 1003 (P0) contains a time instant counter1310; the communication control unit 1004 (S1) contains a time instantcounter 1410; and the communication control unit 1007 (S2) contains atime instant counter 1710.

A reference time instant is transmitted/received from the GPS receiver1015 to the communication control unit 1003 (P0) via a reference timeinstant signal 1016. The reference time instant signal 1016 correspondsto such a signal whose bit is correctly inverted every 1 second. A timecounter 1310 is such a counter which counts up a count value every 1millisecond. The reference time instant signal 1016 is inputted to thetime counter 1310, and is used in order to correct a time instant. Whenthe reference time instant signal 1016 is changed at a time instant“tt1”, digits of the time counter 1310, which are smaller than 1 second,are discarded, or rounded off so as to correct a time instant. Everytime 1 second has elapsed, the communication counter 1310 requests thecommunication control circuit 1039 to transmit a time instantsynchronization to the control bus 1002 (communication channel 1) onetime. At a time instant “tc1” when the communication control circuit1039 accepts a communication command, the communication control circuit1039 transmits time instant synchronization “R (ALL, TMS).”

The time instant synchronization R (ALL, TMS) is constituted by a timeinstant synchronization command TMS, a send key (SendKey=0), a receivekey (Rcv.Key=All), and a time instant (Time). The receive key(Rcv.Key=ALL) indicates that such a key is received by the communicationcontrol units 1004 (S1) and 1007 (S7), which are connected to thecontrol bus 1002 (communication channel 1). The time instant (Time)corresponds to a value which is read out from the time counter 1310 atthe time instant “tc1.”

At a time instant “tt2”, both the communication control units 1004 (S1)and 1007 (S2) recognize that an instruction is issued to the ownequipments, and set the time instant (Time) to the time counters 1410and 1710 so as to perform a time instant synchronization. Both thecommunication control units 1004 (S1) and 1007 (S2) do not echo back thetime instant (Time). The communication control unit 1003 (P0) transmitsnext data.

FIG. 28 shows a communication structure of a peripheral region of theinput/output bus 1005 (communication channel 2). It should also beunderstood that the same reference numerals shown in FIG. 23 will beemployed as those for denoting the same structural elements of FIG. 28,and descriptions thereof are omitted. An input time instant buffer 1486has been added to the structure shown in FIG. 23. Time stamp settinginformation 1485 is constituted by a device number 14852, and a timestamp validity 14853. Both the device number 14852 and the time stampvalidity 14853 are set from the communication control unit 1003 (P0) viathe control bus 1002 (communication channel 1) when the controlapparatus is initiated.

FIG. 29 indicates operation sequences for permitting/stopping dataupdating operation with respect to the input buffers 1092, 1102, 1112 (1to n) via the control bus 1002 (communication channel 1) and theinput/output bus 1005 (communication channel 2). Among data strings andsymbols of time instants shown in the drawing, the same names imply thesame contents as those shown in FIG. 24, and descriptions thereof areomitted.

In order to save such a present time instant when an input freezingoperation is commenced in the input device at a time instant “ti2 a”,the communication control unit 1004 (S1) stores the present time (“Tn”)which has been stored in the time instant counter 1410 into the inputtime instant buffer 1486.

The communication control unit 1004 (S1) transmits input access data IA.

If the relevant input device becomes a time stamp validity based uponthe device number 14852 and the time stamp validity 14853, then the timeinstant (Time) is added.

When the communication control unit 1003 (P0) receives the input accessdata IA, if the relevant input device becomes a time stamp validitybased upon the device number 14852 and the time stamp validity 14853,then the time instant (Time) is written in the input time instant buffer1386 by the communication control unit 1003 (P0). Thereafter, thecommunication control unit 1003 (P0) forms a time stamp.

With execution of the above-described operation sequence, the centralprocessing unit 1001 (CPU) can establish a relationship between theinput data and the time stamp as follows: That is, the input triggercommand of the central processing unit 1 (CPU) is transferred via thecontrol bus 1002 (communication channel 1) and the input/output bus 1005(communication channel 2) to the input unit so as to stop/permit thedata updating operation of the input buffers; the communication controlunit 1004 (S1) acquires that the event occurs in the input device as thetime instant; and then, the communication control unit 1003 (P0) judgesthat the event occurs via the control bus 1002 (communication channel2), and writes the time stamp in the time stamp memory 1387.

Seventh Embodiment

Referring now to FIG. 30 and FIG. 31, a description is made of a methodcapable of realizing that a time stamp is added to read back datacorresponding to output data, according to a seventh embodiment of thepresent invention.

FIG. 30 shows a communication structure of a peripheral region of theinput/output bus 1008 (communication channel 2). It should also beunderstood that the same reference numerals shown in FIG. 25 will beemployed as those for denoting the same structural elements of FIG. 30,and descriptions thereof are omitted. An output time instant buffer 1789has been added to the structure shown in FIG. 25. Time stamp settinginformation 1785 is constituted by a device number 17852, and a timestamp validity 17853. Both the device number 17852 and the time stampvalidity 17853 are set from the communication control unit 1003 (P0) viathe control bus 1002 (communication channel 1) when the controlapparatus is initiated.

FIG. 31 indicates operation sequences for permitting/stopping dataupdating operation with respect to the output buffers 1123, 1133, 1143(1 to n) via the control bus 1002 (communication channel 1) and theinput/output bus 1008 (communication channel 2). Among data strings andsymbols of time instants shown in the drawing, the same names imply thesame contents as those shown in FIG. 26, and descriptions thereof areomitted.

In order to save such a present time instant when an output updatingoperation is commenced in the output device at a time instant “fq8 a”,the communication control unit 1007 (S2) stores the present time (“Tn”)which has been stored in the time instant counter 1710 into the outputtime instant buffer 1789.

The communication control unit 1007 (S2) transmits output read backaccess data IA.

If the relevant input device becomes a time stamp validity based uponthe device number 17852 and the time stamp validity 17853, then the timeinstant (Time) is added.

When the communication control unit 1003 (P0) receives the output readback access data IA, if the relevant output device becomes a time stampvalidity based upon the device number 13852 and the time stamp validity13853, then the time instant (Time) is written in the output timeinstant buffer 1389 by the communication control unit 1003 (P0).Thereafter, the communication control unit 1003 (P0) forms a time stamp.

With execution of the above-described operation sequence, the centralprocessing unit 1001 (CPU) can establish a relationship between theoutput data and the time stamp as follows: That is, the output updatingcommand of the central processing unit 1 (CPU) is transferred via thecontrol bus 1002 (communication channel 1) and the input/output bus 1008(communication channel 2) to the output unit so as to stop/permit thedata updating operation of the output buffers; the communication controlunit 1007 (S2) acquires that the event occurs in the output device asthe time instant; and then, the communication control unit 1003 (P0)judges that the event occurs via the control bus 1002 (communicationchannel 2), and writes the time stamp in the time stamp memory 1387.

The fourth, fifth, sixth, and seventh embodiments of the presentinvention have described such a system that the time stamps are acquiredwhen the designated events occur. Next, a description is made of systemsfor repeatedly acquiring time stamps without especially designating anevent.

Eighth Embodiment

Referring now to FIG. 32, FIG. 23, FIG. 24, a description is made of aneighth embodiment according to the present invention.

A description is made of a different point with respect to theabove-described fourth embodiment of the present invention.

FIG. 32 shows an internal arrangement of the communication control unit1003 (P0). It should be noted that the same reference numerals shown inFIG. 22 will be employed as these for denoting the same structuralelements shown in FIG. 32, and thus, explanations thereof are omitted.

Time stamp validities 13853 have been allocated to the time stampsetting information 1385 every input/output devices.

One set of a valid bit 13871, data 13872, and a time instant 13873 hasbeen allocated to a time stamp memory 1387 every input/output devices.

FIG. 23 shows a communication structure of a peripheral region of theinput/output bus 1008 (communication channel 2). It should also beunderstood that the same reference numerals shown in the fourthembodiment of FIG. 23 are employed and descriptions thereof are omitted.

FIG. 24 indicates a time chart for explaining input operations of theeighth embodiment. A different point of this eighth embodiment from thefourth embodiment is a judgement of a time stamp at a time instant“ti4”, and a time stamp forming method.

In the time instant “ti4”, if the input data comparison is madecoincident with each other, when the time stamp validity 13853 becomesvalid, then a device time stamp is formed in the time stamp memory 1387to which the relevant input device has been allocated. A “valid” symbolis written in the valid bit 1371; input data is written in the data13872; and a value read from the input time buffer 1386 is written inthe time instant 13873.

In accordance with the above-described operation sequences, the inputtrigger command of the central processing unit 1001 (CPU) is transferredvia the control bus 1002 (communication channel 1) and the input/outputbus 1005 (communication channel 2), stop/permit the data updatingoperations of the input buffers, and the data inputted in the inputdevice and the time instant are inputted in the time stamp memory 1387,so that the central processing unit 1001 can establish a relationshipbetween the input data and the time stamp.

Ninth Embodiment

Referring now to FIG. 32, FIG. 25, FIG. 26, a description is made of aninth embodiment according to the present invention.

A description is made of a different point with respect to theabove-described fifth embodiment of the present invention.

FIG. 32 shows an internal arrangement of the communication control unit1003 (P0). It should be noted that the same reference numerals shown inthe eighth embodiment of FIG. 32 are the same structural elements ofthis ninth embodiment, and thus, explanations thereof are omitted.

FIG. 25 shows a communication structure of a peripheral region of theinput/output bus 1008 (communication channel 2). It should also beunderstood that the same reference numerals shown in the fifthembodiment of FIG. 23 are employed, and descriptions thereof areomitted.

FIG. 26 indicates a time chart for explaining output operations of theninth embodiment. A different point of this ninth embodiment from thefifth embodiment is a judgement of a time stamp at a time instant“tq11”, and a time stamp forming method.

Both the time stamp judging operation and the time stamp formingoperation of this ninth embodiment are identical to those of the eighthembodiment.

In accordance with the above-described operation sequences, the outputupdating command of the central processing unit 1001 (CPU) istransferred via the control bus 1002 (communication channel 1) and theinput/output bus 1005 (communication channel 2), stop/permit the outputdata updating operations of the output buffers, and the time instant andthe data (read back) outputted in the output device are inputted in thetime stamp memory 1387, so that the central processing unit 1001 (CPU)can establish a relationship between the output data and the time stamp.

Tenth Embodiment

Referring now to FIG. 32, FIG. 33, FIG. 24, a description is made of atenth embodiment according to the present invention.

A description is made of a different point with respect to theabove-described sixth embodiment of the present invention.

FIG. 32 indicates an internal arrangement of the communication controlunit 1003 (P0). It should be noted that the same reference numerals ofthe eighth embodiment shown in FIG. 32 are employed, and thus,explanations thereof are omitted.

FIG. 33 shows a communication structure of a peripheral region of theinput/output bus 1008 (communication channel 2). The time stamp settinginformation 1485 of this tenth embodiment is different from that of FIG.28. The time stamp setting information 1485 is constituted by the timestamp validity 14853.

FIG. 29 indicates a time chart for explaining input operations of thetenth embodiment. A different point of this tenth embodiment from thesixth embodiment is a judgement of a time stamp at a time instant “ti4”,and a time stamp forming method.

Both the time stamp judging operation and the time stamp formingoperation of this tenth embodiment are identical to those of the eighthembodiment.

In accordance with the above-described operation sequences, the inputtrigger command of the central processing unit 1001 (CPU) is transferredvia the control bus 1002 (communication channel 1) and the input/outputbus 1005 (communication channel 2), stop/permit the data updatingoperations of the input buffers, and the data and the time instantentered in the input device are inputted in the time stamp memory 1387,so that the central processing unit 1001 (CPU) can establish arelationship between the input data and the time stamp.

Eleventh Embodiment

Referring now to FIG. 32, FIG. 34, and FIG. 31, a description is made ofan eleventh embodiment according to the present invention.

A description is made of a different point with respect to theabove-described seventh embodiment of the present invention.

FIG. 32 indicates an internal arrangement of the communication controlunit 1003 (P0). It should be noted that the same reference numerals ofthe eighth embodiment shown in FIG. 32 are employed, and thus,explanations thereof are omitted.

FIG. 34 shows a communication structure of a peripheral region of theinput/output bus 1008 (communication channel 2). The time stamp settinginformation 1485 of this eleventh embodiment is different from that ofFIG. 28. The time stamp setting information 1485 is constituted by thetime stamp validity 14853.

FIG. 31 indicates a time chart for explaining output operations of theeleventh embodiment. A different point of this eleventh embodiment fromthe seventh embodiment is a judgement of a time stamp at a time instant“tq11”, and a time stamp forming method.

Both the time stamp judging operation and the time stamp formingoperation of this eleventh embodiment are identical to those of theeighth embodiment.

In accordance with the above-described operation sequences, the outputupdating command of the central processing unit 1001 (CPU) istransferred via the control bus 1002 (communication channel 1) and theinput/output bus 1005 (communication channel 2), stop/permit the outputdata updating operations of the output buffers, and the time instant andthe data (read back) outputted in the output device are inputted in thetime stamp memory 1387, so that the central processing unit 1001 (CPU)can establish a relationship between the output data and the time stamp.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

The invention claimed is:
 1. A control apparatus having a communicationcontrol unit communicatably connected to a first communication channel,at least a portion of which constitutes a serial transfer operation, inwhich said communication control unit at least one of transmits andreceives information with respect to an equipment under control via asecond communication channel, a portion of which constitutes a paralleltransfer operation, said control apparatus comprising: a communicationchannel diagnostic unit for diagnosing an abnormal event including anopen and stuck-at of a parallel transfer portion of said secondcommunication channel under such a condition that a data transferoperation in the second communication channel is interrupted; wherein asignal for instructing an initiation of a diagnosis via said firstcommunication channel is transmitted to said communication channeldiagnostic unit; wherein said control apparatus is further comprised ofan intermediary station; wherein at least any one of data transmittedfrom the communication control unit via said first communication channelbeing transmitted via said intermediary station to said equipment undercontrol, and data sent from the equipment under control beingtransmitted via the intermediary station from the communication controlunit to the first communication channel is available; and wherein saiddiagnosis corresponds to at least any one of the parallel transfer pathbetween the communication control unit and the intermediary station, andthe parallel transfer path between the intermediary station and saidequipment under control.
 2. A control apparatus having a communicationcontrol unit communicatably connected to a first communication channel,at least a portion of which constitutes a serial transfer operation, inwhich said communication control unit at least one of transmits andreceives information with respect to an equipment under control via asecond communication channel, a portion of which constitutes a paralleltransfer operation, said control apparatus comprising: a communicationchannel diagnostic unit for diagnosing an abnormal event including anopen and stuck-at of a parallel transfer portion of said secondcommunication channel under such a condition that a data transferoperation in the second communication channel is interrupted; wherein asignal for instructing an initiation of a diagnosis via said firstcommunication channel is transmitted to said communication channeldiagnostic unit; wherein said communication control unit receives thediagnosis instruction via said first communication channel so as toinitiate said diagnosis; and wherein said communication control unitreturns a message via said first communication channel with respect tothe diagnosis instruction received via said first communication channel,and initiate said diagnosis.
 3. The control apparatus as claimed inclaim 2, wherein said communication control unit interrupts the datatransmission and/or reception between the central processing unit andthe equipment under control via said first communication channel,initiates said diagnosis, and restarts said data transmission and/orreception after said diagnosis is accomplished.
 4. A control apparatus,comprising: a communication control unit, communicatably connected to afirst communication channel and second communication channel, configuredto conduct a transfer operation through the first communication channelduring which said communication control unit at least one of transmitsand receives information with respect to an equipment under control viathe second communication channel, and also configured to conduct atransfer operation through the second communication channel; and acommunication channel diagnostic unit, configured to diagnose anabnormal event, including either of an open or a stuck-at paralleltransfer operation through said second communication channel, when adata transfer operation in the second communication channel isinterrupted; wherein upon said communication channel diagnostic unitreceiving an instruction, transmitted via said first communicationchannel, to initiate a diagnosis of an abnormal event in said secondcommunication channel, said communication control unit is configured toreturn a message via said first communication channel that the diagnosisinstruction has been received via said first communication channel, andto initiate said diagnosis.
 5. The control apparatus as claimed in claim4, wherein said communication control unit is configured to interruptthe data transmission and/or reception between the central processingunit and the equipment under control via said first communicationchannel, to initiate said diagnosis, and to restart said datatransmission and/or reception after said diagnosis is accomplished.